We're bringing to an end our live text coverage of a gun attack on the offices of satirical magazine Charlie Hebdo in Paris, which left 12 people dead. French police are still hunting for two brothers, Said and Cherif Kouachi, in connection with the attack, after another suspect reportedly handed himself in. We'll continue to bring you updates on our main story page. Thanks for following the story on BBC News.
Neelabh Banerjee Horrible attack. Cartoonists across the world are uniting against bloodshed and violence.
Joey Tranchina sent in this photo of the vigil held in Sète, France.
Hamed Saeedi: In my Islamic upbringing I was taught that the pen is man's strongest weapon. These extremists must know that they can never silence freedom of speech, for it is a stronger weapon than any they'd dare to carry. Why couldn't they answer peacefully through the pen as our prophet likely would have? True Islam condemns such attacks, more so when they are ignorantly and violently carried out in its name. Long live freedom of expression, religious tolerance and peaceful coexistence.
We've put together a selection of eyewitness accounts from those who were present during the attack in Central Paris on Wednesday. One of the magazine's illustrators, Corinne Rey, said two armed, masked men "brutally threatened" her in order to gain access to the building. The gunmen "spoke perfect French" and claimed to belong to al-Qaeda, according to Ms Rey.Copyright: AP
- Copyright: Reuters
Police officers stand guard outside a flat in Reims as investigators search inside.
- Copyright: FRENCH POLICE
French police have released these photos of the two brothers wanted in connection with the attacks. Cherif Kouachi (l) is 32, and his brother Said is 34.
French police have issued arrest warrants for brothers Cherif Kouachi, 32, and Said Kouachi, 34, AFP says. They have appealed to the public for information but warned that the men were "likely armed and dangerous".
A hashtag called #MouradHamydInnocent is trending in France, reportedly started by classmates of 18-year-old Hamyd Mourad who say they were in class with him at the time of the attack.
Sources tell AFP that 18-year-old Hamyd Mourad surrendered to police at 23:00 local time on Wednesday "after seeing his name circulating on social media". "He has been arrested and taken into custody," another source told the agency.
Nihaad Hosany: It's so awful. Because of three idiots, three terrorists, the Muslim community will suffer again. Islam is a religion of peace and understanding. Not this monstrosity. It's really awful that people are capable of such acts. My deepest sympathies to the families.
Hamyd Mourad, the youngest of the three suspects. has surrendered to police, sources tell AFP.
- Copyright: Reuters
Rallies condemning the attack are taking place across the world, including this one in Quebec, Canada.
- Copyright: Alex Green
Alex Green sent in this cartoon.
Mehboob Mirza: It is a sad & tragic day. RIP. What is more insulting to the Prophet (peace be upon him) than satirical cartoons are those who murder innocent people in his name.
France 2 TV reporter
has tweeted this picture of police searching a flat in Reims, where an anti-terror raid is taking place.Copyright: @hugoclement
Police say the three suspects they are pursuing in connection with the attack are Hamyd Mourad and brothers Said Kouachi and Cherif Kouachi.
@BBCTrending have put together a gallery of cartoonist's responses to the Charlie Hebdo attack.Copyright: Satish Acharya
tweets: "One minute of silence for #CharlieHabdo in Place Garibaldi in Nice"Copyright: ALICE PATALACCI
French soldiers disembark at Le Bourget airport, north of Paris, as part of a deployment of soldiers to enhance security in Paris.Copyright: AP
France 3 TV journalist
is in Reims where a police anti-terror raid is taking place and has tweeted this picture from the scene:Copyright: @MisterCHCH
Meryl Cumins: Commiserations to the injured and the families of the dead. Fraternity, Equality and most of all, Liberty. Where freedom of speech is an alien concept there can be only tyranny.
AFP has more details from that police raid reportedly taking place in Reims in north-eastern France. A member of France's elite anti-terror unit has called on journalists at the scene to remain "vigilant", warning that there would "a showdown" or that the suspects could escape, the agency says.
- Copyright: BBCCopyright: BBCCopyright: BBCCopyright: BBC
tweets: Multiple reports of police raids in Reims as police search for #CharlieHebdo suspects, 1 of 3 identified is from Reims
Police say an anti-terror raid is under way in the north-eastern city of Reims, according to the AFP news agency.
- Copyright: BBCCopyright: BBCCopyright: BBCCopyright: BBCCopyright: BBC
BBC correspondent Fergal Keane reports that tensions over the role of Islam have "sharpened" in France over recent years.
He adds: "Along with that there is resentment over French policy in the Arab world which has radicalised many youth."
The BBC's Hugh Schofield has written about how the attack on Charlie Hebdo will be felt in France.
He says today "will remain engraved in the national memory."Copyright: BBC
In response to Wednesday's attack, at least three Danish newspapers are planning to print copies of cartoons from Charlie Hebdo, according to the BBC's Malcolm Brabant in Copenhagen.
But none of the Copenhagen press are planning to reprint the 12 Danish cartoons of the Prophet Muhammad that ignited anger in some areas of the Muslim world seven years ago. Yet security has been tightened at all of the country's media outlets as a result of the massacre.
The editor of the tabloid BT said he would be running with Charlie Hebdo's most controversial cover - one that showed a weeping Muhammad overwhelmed by fundamentalists, lamenting that it was hard being loved by idiots.
BBC News website reader: My heart bleeds and I'm shaken to the core by what happened to fellow journalists that only did their job (and did it well).
Former CIA counter-terrorism analyst Aki Peritz tells BBC World News that that the attacks appear to have been "very professional, well thought out, well researched and well executed".
He says it is significant that apart from the police, the only other targets were journalists and nobody else inside the Charlie Hebdo office was killed.
The Paris Normandie newspaper has expressed its solidarity with those killed in today's attack, publishing a front page which alters the name of the publication in honour of Charlie Hebdo.Copyright: PAris normandie
Roger Collinge: As an ordinary citizen lucky enough to live in a country with free speech I join my name in support of this magazine and all who work for it with deepest sympathy to those who have suffered from this horror. Freedom of speech means what it says. It includes the right to be scurrilous and silly but it must remain. Those who oppose freedom of speech must be defeated.
Joachim: My thoughts are with Paris tonight. My pen will be firmly in the air.
The BBC's Security Correspondent Frank Gardner says that the Charlie Hebdo attack did not come out of the blue. It comes after a string of recent attacks, albeit less high-profile and resulting in fewer casualties.Copyright: BBC
Reuters is reporting more details on the three suspects being sought by French police. Officers are looking for two brothers in the Paris region and another man in the north-eastern city of Reims, according to the news agency. It quotes a government source as saying the two brothers are 32 and 34 years of age and the third suspect is 18 years old.
Le Monde reports that police sources have said that the three gunmen have been identified.
Caroline Wyatt, BBC Religious affairs correspondent has just posted this:
The killings at Charlie Hebdo are a deeply unwelcome reminder to the west that for some, mainly young radicalised men, their fundamentalist interpretation of their religion matters enough to kill those who offend it.
As a result, across western Europe, liberally-minded societies are beginning to divide over how best to deal with radical Islamism and its impact on their countries, while governments agonise over the potential for a backlash against Muslims living in Europe.
Today, mainstream Muslim organisations in the UK and France have unequivocally condemned the killings, saying that terrorism is an affront to Islam.
But the potential backlash, including support for far right parties and groups, may well hurt ordinary Muslims more than anyone else, leaving the authorities and religious leaders in western Europe wondering how to confront violence in the name of religion without victimizing minorities or being accused of "Islamophobia".
Caroline Wyatt's full piece can be read here:
The BBC's Paris correspondent Hugh Schofield says that France has just lived through "one of those days which remain engraved in the national memory".
He adds: "Today everyone can share in the common defence of French values...But how long this unity will last is another question.
"Soon there will be the discordant voices. On the one hand there will be those saying the real lesson of the attack is that France should drop its 'naivety' concerning Islamism in the banlieues.
"On the other side there will be those warning against what the French call l'amalgame - i.e. lumping all Muslims together and claiming that the problem resides somewhere with their religion."
- Copyright: Reuters
People attending a rally in Trafalgar Square, central London, have been singing La Marseillaise, France's national anthem.
- Copyright: Sruthi Gottipati
Journalist Sruthi Gottipati took this photo in Paris, France.
Eric Albert tells the BBC News Channel he fears what will happen over the coming days in France due to what he calls the "malaise" afflicting society.
"There will be unity for a while because of the horror and shock," he said. "What's going to happen after that?"
President Hollande, in a brief address, said that "nothing can divide us, nothing can separate us".
He added: "We will win. Nothing will make us renounce our determination. Long live the republic. Long live France."Copyright: Reuters
President Francois Hollande is making a televised address to the nation. He has announced a national day of mourning on Thursday.
Rallies have been taking place across Europe in support of Charlie Hebdo. From top, a protester in Lausanne, Switzerland; the European Parliament in Brussels; Trafalgar Square in central London; a rally outside the French embassy in Madrid.Copyright: EPACopyright: ReutersCopyright: PACopyright: AFP
Agence France Presse tweets pictures from inside their newsroom in Paris, where journalists held a minute's silence holding "Je Suis Charlie" posters:Copyright: AFPCopyright: AFPCopyright: AFP
Google France has added a black ribbon to its homepage following today's attacks.Copyright: Google
A number of cartoonists have drawn images responding to today's attack on Charlie Hebdo, expressing support and solidarity with the magazine and principles of free speech and freedom of expression.Copyright: TwitterCopyright: TwitterCopyright: TwitterCopyright: TwitterCopyright: TwitterCopyright: Twitter
BBC Security Correspondent Frank Gardner notes that the attack has not come out of the blue. The journalists behind Charlie Hebdo had plenty of enemies, he says, and its decision to publish a string of cartoons deemed offensive by some Muslims had made it a target for Islamist extremists.
Orlando: Over a thousand people have said they will be in Trafalgar Square from 6pm this evening. I think it could be a lot more as not everyone has had time to log into FB. I'll be there with 4 friends.
The United Nations Security Council has joined the chorus of condemnation, calling the attack "barbaric and cowardly".
The Globe and Mail's Mark MacKinnon took this picture at the Place de la Republique in Paris, where crowds are gathering to express solidarity with the magazine:Copyright: Mark MacKinnon
- Copyright: BBC
Steve Bell tells BBC News channel: "We've got to stand up for the right to take the piss out of these monsters, these idiots, these fools, these posturing maniacs who strut around in their black gear as a kind of death cult trying to frighten us all."
Prosecutor Francois Molins declines to give details of the investigation:
"The idea is to keep confidentiality and make sure this inquiry is successful, so we have to try to arrest the individuals that committed these murders as soon as possible."Copyright: AFP
The Charlie Hebdo website has published a pdf file translating the solidarity message "Je suis Charlie" into several languages, including Arabic.Copyright: Charlie Hebdo
- Copyright: Robin Jouan
@Robin ANEMF took this photo of a demonstration in Nice, France.
Large crowds are gathering in Place de Republique in central Paris following the attack on Charlie Hebdo magazine's office.Copyright: AFP
The BBC has put together a photo gallery of the attack today at Charlie Hebdo magazine:Copyright: BBC
French football club Lille has said it will hold a minute's silence before its forthcoming match against Evian. Both clubs are due to wear black armbands for the tie.
People are holding up pens and pencils at a rally in Paris's Republic Square.Copyright: AFP
British newspaper The Independent tweets that there will be a vigil in London's Trafalgar Square this evening in solidarity with Charlie Hebdo magazineCopyright: Twitter
- Copyright: BBC
The editor of British satirical magazine Private Eye Ian Hislop has released a statement to the British press on the Charlie Hebdo attacks.
"I am appalled and shocked by this horrific attack - a murderous attack on free speech in the heart of Europe.
I offer my condolences to the families and friends of those killed - the cartoonists, journalists and those who were trying to protect them.
They paid a very high price for exercising their comic liberty.
Very little seems funny today."
BBC Trending has published a post looking into Charlie Hebdo's mysterious final tweet before the attack in Paris.
"Is it just a coincidence that this image was tweeted at around the time of the attack? The illustration bears the signature of Honoré, a famous French illustrator - but it's unclear whether it's his work or when it was actually drawn. BBC Trending has tried to contact Honoré and will post an update if we hear back from him."Copyright: Julia Macfarlane
Luc Bronner, an editor from Le Monde, has tweeted a copy of a joint statement from Radio France, Le Monde and France Télévisions offering technical support to help Charlie Hebdo continue working after today's attack.
- Copyright: Marine Duc
@marchanddenuage took this photo of a demonstration in Lyon, France.
emails: Simply to add our name to the growing list of publishers who in their own small way offer their support to the friends and family of those journalists who were killed and injured in today's attack in Paris. My father fought in WW2 along with many others to secure all our freedoms - freedom of speech being the upmost freedom.
Despite speculation that the attack was a response to Charlie Hebdo's run of controversial cartoons, some publications are taking the decision to reprint them. In Egypt, the daily Al Masry Al Youm newspaper has run a selection of the magazine's illustrations - including the recent cartoon lampooning Abu Bakr al-Baghdadi, the leader of Islamic State.
Le Monde has run the following cartoon from Plantu, one of its regular illustrators, in tribute to the victims of today's attack. It says "With Charlie Hebdo, wholeheartedly."Copyright: Le Monde
@chrisPcritttertweets: Much respect to #CharlieHebdo for their bravery and fearlessness in their mission and art. #JeSuisCharlie
Hassan Chalghoumi - an imam of the Paris suburb of Drancy, visited the site of the attack at Charlie Hebdo headquarters.
Of the attackers, he said: "Their prophet is Satan. There is no connection between the Islamic faith and this minority."Copyright: AFP
The Booker Prize-winning writer has released the following statement: "Religion, a mediaeval form of unreason, when combined with modern weaponry becomes a real threat to our freedoms.
"This religious totalitarianism has caused a deadly mutation in the heart of Islam and we see the tragic consequences in Paris today.
"I stand with Charlie Hebdo, as we all must, to defend the art of satire, which has always been a force for liberty and against tyranny, dishonesty and stupidity.
"'Respect for religion' has become a code phrase meaning 'fear of religion.' Religions, like all other ideas, deserve criticism, satire, and, yes, our fearless disrespect."
Charlie Hebdo typified the long-running tradition of scurrilous French satire. Here is one of its more provocative front pages from 2012, showing an Orthodox Jew pushing an old Muslim in a wheelchair, both shouting "You mustn't make fun!"Copyright: charlie hebdo
A reminder, we profile the magazine here:
Adam: For those who know Charlie Hebdo they are a satirical publication. They cover any topics, any religion. Does a small group of lunatics really think they can shut freedom of speech and press with their violence?
The horrific attack at the Charlie Hebdo office on January 7, 2015, led to the death of 12 people, including two policemen.
Nothing can justify such an attack and those who organised and committed these crimes should be brought to justice, Human Rights Watch said.
France should protect freedom of expression and guard against any backlash against particular groups.
Many sources are now reporting that French economist and writer Bernard Maris is among the dead following today's shooting.
The Charlie Hebdo website is back online after reportedly being down following the attack in Paris.
It now shows the single image "Je Suis Charlie" ("I Am Charlie"), which has been trending worldwide on social media.Copyright: charlie hebdo
@MFKerrtweets: Someone is trying to prove that the sword is mightier than the pen. It will be if we don't all fight back. #CharlieHebdo
More John Kerry reaction: "Free expression and a free press are core values. They are universal principles that can be attacked, but never eradicated.
"Today's murders are part of a large confrontation...between civilisation itself, and those opposed to the civilised world."
A police spokesman, Emmanuel Quemener, has been giving more details about the investigation:
"We have descriptions; our colleagues at the judicial police are in contact with the people who were present at the time of the event. These people will be interrogated, it involves a group of three hooded suspects with heavy weapons who fled the scene before they could be arrested."
"Unfortunately they came across colleagues in police cars, on whom they opened fire. There were colleagues who retaliated. They [the suspects] succeeded in spite of everything to escape, currently they are actively trying to find them."
US Secretary of State John Kerry is speaking about the attacks.
He said: "We stand with you in solidarity and in commitment both to the cause of confronting extremism and in the cause which the extremists fear so much and which has always united our two countries: freedom."
French newspaper L'Humanite has spoken to designer Corinne Rey who says she was at the building at the time of the attack.
She describes how two gunmen threatened her in order to gain access to the building by forcing her to type in the entrance code.
Today's attack has drawn sympathy from across the globe. In Berlin a floral tribute has been left outside the French Embassy.Copyright: EPA
tweets: In response to the #CharlieHebdo massacre we must not suppress liberties in the name of defending them - that's what the terrorists want
- Copyright: Robert Mankoff, New Yorker
This cartoon of an empty box taken from the New Yorker has been tweeted thousands of times
The Arab League and Al-Azhar, Sunni Islam's most prestigious centre of learning in Egypt, both issued statements:
"Arab League chief Nabil al-Arabi strongly condemns the terrorist attack on Charlie Hebdo newspaper in Paris."
Al-Azhar condemned the "criminal attack," saying that "Islam denounces any violence".
French journalist Soren Seelow tweets: Spontaneous rally at Republic Square after the attack on Charlie HebdoCopyright: Twitter
The BBC has profiled the Charlie Hebdo editor Stephane Charbonnier, who was killed in the attack in Paris.Copyright: BBC
Footballer Vincent Kompany, the Manchester City and Belgium captain, is among those using the #JeSuisCharlie hashtag to express solidarity with the victims of today's shooting.
An attack similar to the one in Paris could happen in the UK, according to Mohammed Shafiq from the Ramadhan Foundation, which works with young British Muslims. He said "the thing that keeps me up at night is the fact that we have these lone wolves".
The most recent tweet from Charlie Hebdo's official account was an image of a cartoon depicting the leader of Islamic State, Abu Bakr al-Baghdadi, with the words, "Best wishes, by the way. To you too, al-Baghdadi," while he says, "especially to your health."
It is not known at this stage if the tweet has any connection to the attack which was reported to have started around the same time.
BBC Trending is looking in detail at social media amid the attack.Copyright: Twitter
Trade unionists at Syndicat National des Journalistes want newsrooms to observe a moment of silence. They said of the attack: "When journalists are killed, it is done to make an entire profession feel fear; it is done to silence".
Russian President Vladimir Putin has condemned "this cynical crime" and offered his condolences to the victims and their families.
French far right leader Marine Le Pen has said she will release a statement on today's shootings at 4.30pm French time.
tweets: As a Muslim, I condemn the cruel attack on #CharlieHebdo & offer condolences to the French people. The "Islam" of the murderers is not mine.
US President Barack Obama has condemned the Paris attack and what he calls "the hateful vision of these killers".
@siobhanheanue tweets: Parisians will take to the streets tonight, for freedom of the press, democracy and the Republic #CharlieHebdo
Reuters is reporting that Jyllands-Posten, the Danish newspaper that triggered protests in some Muslim countries after publishing cartoons of the Prophet Muhammad, has increased its security following today's attack.
French Interior Minister Bernard Cazeneuve is currently giving a statement. He says that the authorities are hunting three attackers in connection with the shooting.
Anne Hidalgo, the mayor of Paris, has released a statement on Facebook condemning the attack and calling for a march on Thursday through Paris's Republic Square at 6pm.
She says: "I feel a sense of absolute horror at the attack... We must respond to this act through the sacred union around the principles of the Republic."Copyright: facebook
People are using the hashtag "#JeSuisCharlie" (I am Charlie) to express sympathy for the people killed in the attack in Paris.Copyright: Twitter
Jacques Myard, French MP with opposition party UMP, said: "We knew something would happen. The (security) services used to say to us it's not if but when and where. We know that we are at war. The Western nations - like Britain, France, Germany - we are at war."
French Justice Minister Christiane Taubira reacts outside the headquarters of Charlie Hebdo.Copyright: AFP
Stephane Charbonnier, the magazine's editor-in-chief reportedly killed in the attack, had received death threats in the past and was living under police protection.
More from the US: White House spokesman Josh Earnest told CNN he condemned the attack in the strongest possible terms. "It's not just an attack on the people of France, it's an attack on some of the basic values we hold dear in this country - freedom of speech, freedom of expression and a free press."
@rayverma tweets: #Paris, you're on my mind. The darkest moment in the history of French media. To my French family - stay safe. #ParisShooting #CharlieHebdo
The French government has sent soldiers to protect public spaces in Paris.Copyright: AFP
Three other cartoonists killed have been named by AFP as Jean Cabut ("Cabut"), Bernard Verlhac ("Tignous") and Georges Wolinski ("Wolinski").
The director of Le Monde newspaper, Gilles Van Kote, has condemned the attack on Charlie Hebdo, saying: "The killing that occurred [today] only reinforces our belief that it is necessary to fight against ignorance, intolerance, obscurantism and fanaticism. It is more vital than ever to remember that freedom of the press is not negotiable."
Danish cartoonist Kurt Westergaard, whose work depicting the Prophet Muhammad was reprinted in Charlie Hebdo, said he hoped "the moderate majority of Muslims" would condemn the attack.
BBC Trending has pulled together some of the tweets to emerge from the attack.
The editor-in-chief of Charlie Hebdo, Stephane Charbonnier, known as Charb, has reportedly been killed in the attack, judicial sources tell Agence France Presse.
Video of the gunmen fleeing the attack has emerged.
People stand outside the French satirical newspaper Charlie Hebdo's office after the shooting.Copyright: AP
French politician Philip Cordery said a democratic freedom had been attacked: "Not only France, the whole of Europe is under shock today because by doing this horrendous act, the terrorists are once again attacking one of the important symbols of freedom, which is freedom of the press... and I think it's important for all democrats to unite and fight strongly against terrorism."
Fiamnetta Venner, who used to work at Charlie Hebdo, tells the BBC that journalists at the magazine had been afraid such an attack might happen: "We all were frightened of this moment, and this moment arrived. All of our friends who died, each day we will integrate them inside us. But I think they have just woken up an entire nation, because it's a generation of artists, of journalists who disappeared today."
French President Francois Hollande (centre left), flanked by Interior Minister Bernard Cazeneuve (right), walk outside the French satirical newspaper Charlie Hebdo's office in Paris.Copyright: AP
Echoing the language of other world leaders, Nato Secretary General Jens Stoltenberg called the attack "a barbaric act and an outrageous attack on press freedom".
More from Chancellor Merkel: "I'm shocked to receive the news of the malicious attack on a newspaper office in Paris. In these hours of pain I would like to express to you and your countrymen the sympathy of the German nation."
Some of the magazine's cartoonists are among the dead, Le Point has reported.
French police officers and forensic experts examine a car used by armed gunmen who stormed the Paris offices of satirical newspaper Charlie Hebdo.Copyright: AFP
The attackers went to the second floor of the Hebdo offices and started firing indiscriminately in the newsroom, Christophe DeLoire of Reporters Without Borders tells AP news agency. "This is the darkest day of the history of the French press," he said.
Italian President Matteo Renzi has added his voice to international condemnation of the attack, tweeting that "violence will always lose against freedom".
Chancellor Merkel said the shootings in France are not only an attack on French citizens, but on freedoms of the press and speech.
German Chancellor Angela Merkel has condemned the attack as "abominable".
French terrorism expert Jean Charles Brisard tells the BBC that the attack was well planned: "What we can say is, looking at the images and videos that are coming out, is the individuals were well-prepared, well-equipped; they had military-style weapons; they had probably bullet-proof jackets. So these individuals were well trained and determined indeed to commit this terrorist act, which is probably the worst that we've experienced in French history in the last 30 years."
Firemen at the scene of the attack on the Charlie Hebdo offices.Copyright: EPA
"I am profoundly shocked by this brutal and inhuman attack," European Union President Jean-Claude Juncker says.
BBC profile: in French politics
The attack took place as staff held their weekly editorial media, a source has told the France 2 news channel.
@nilicule tweets: Saddened by the amount of anti-Islam commentary in my timeline. Terrorism is not an Islam problem, it's an extremism problem. #CharlieHebdo
France 24 TV is showing amateur footage apparently of the gunmen firing outside the building, running over to a person lying on the pavement and shooting at them while shouting slogans before getting into a car and driving off.
"Everybody here at the White House are with the families of those who were killed or injured in this attack," spokesman Josh Earnest says.
European Union President Jean-Claude Juncker condemns the attack as intolerable and barbaric.
@CorkGourmetGuy tweets: Sickened and saddened by what has happened in Paris, no cause can justify murder, my thoughts are with all @Charlie_Hebdo_ #CharlieHebdo
Police officer stands in front of the offices of the French satirical newspaper Charlie Hebdo.Copyright: Getty Images
Charlie Hebdo was targeted for exercising its right to freedom of speech, journalist Douglas Murray tells the BBC. "I think that a lot about our future freedom of speech depends on whether or not people think that Charlie Hebdo brought this on itself or realise that the people who carried out this attack are solely to blame and must be the subject of vilification from everybody, from all faiths in all of our societies."
A Twitter campaign pledging support for the victims and the French magazine is gaining traction within moments of the first #JeSuisCharlie hashtag being posted.
The White House has condemned the attack
The attack took place in a busy part of Paris, not far from the centre and a passer-by tells the BBC: "The street's [often] used by drivers and Parisians to go from a place to another. The office is actually located in a place where a lot of people are going through."
More pictures have emerged from the scene.Copyright: Reuters
The radical Islamic State group threatened to attack France minutes before Hebdo tweeted a satirical cartoon of the extremist group's leader giving New Year's wishes, AP says.
The masked gunmen who carried out Wednesday's attack committed France's deadliest terror attack in at least two decades, AP says.
French President Francois Hollande (second on the left) talks to the press upon his arrival at the headquarters of the French satirical newspaper Charlie Hebdo.Copyright: AFP
Two of the gunmen were dressed in typical jihadist "uniform" of black balaclavas, khaki ammunition pouches and were armed with Kalashnikovs, the BBC's Frank Gardner reports. They were heard shouting "Allahu Akbar".
The gunmen were armed with Kalashnikovs and a rocket-launcher, AFP reports.
The attack happened in central Paris, near some of the capital's most famous tourist attractions.Copyright: BBC
Gunmen who carried out the attack are still at large, French prosecutor says.
This is the latest edition of the magazine, showing controversial French novelist Michel Houellebecq.Copyright: AFP
Witnesses spoke of sustained gunfire at the Hebdo offices, the BBC's Hugh Schofield in Paris reports, as the attackers opened fire with assault rifles.
The 12 dead include two police officers, police say.
Twelve people have been killed in the attack, police say.
France TV Info says that gunman is heard shouting "God is great" in Arabic in a video of shooting.
People stand outside the French satirical newspaper Charlie Hebdo's office after the shooting.Copyright: AP
More from President Hollande: "We must react with firmness, but with consideration for national unity. We are in a difficult moment - several attacks have been avoided. We knew we were threatened because we are a country of freedom. We will punish the attackers."
Witnesses quoted by French Europe 1 radio say that one of the attackers shouted "The prophet was avenged" while carrying out the assault.
France has reinforced security at places of worship, shops, media offices and transportation, AP reports.
"Nobody in France should think that they can behave against the principle of the Republic and harm the spirit of the Republic, embodied by a newspaper," President Hollande said. "Today I am thinking about the victims - 11 are dead, 4 are fighting for their lives. We should do whatever we can to find those responsible and to call for national unity."
"France today faced a shock," President Hollande said, "which is this is a terrorist operation, by terrorists, against a newspaper that has been threatened several times - and that's why we have to give it the protection it needs."
French President Francois Hollande (R) arrives at the Paris offices of Charlie Hebdo after the shootings.Copyright: Reuters
Gilles Boulanger works in the same building as the Charlie Hebdo offices: "A neighbour called to warn me that there were armed men in the building and that we had to shut all the doors. And several minutes later there were several shots heard in the building from automatic weapons firing in all directions. So then we looked out of the window and saw the shooting was on Boulevard Richard-Lenoir, with the police. It was really upsetting. You'd think it was a war zone."
A French journalist in the Hebdo building who spoke to the BBC has described the situation as "a massacre".
This photograph has emerged of the purported gunmen facing off against police.Copyright: AFP
@SnehaSSneha tweets: The fresh attack on #CharlieHebdo Office clearly shows that the media needs to watch what it shows/speaks! But Why? can't we enjoy a satire?
President Hollande says that French security is now on highest alert and that 11 people are dead, four are critical and 40 others have been taken to safety. He says that one police officer is among the dead.
@lauchlan_s tweets: So sad about the #CharlieHebdo shooting. It's a scary time to be a journalist.
Fire fighters and police are now surrounding the Hebdo offices.Copyright: AFP
French President Francois Hollande has described the attack as a barbarous terrorist incident.Copyright: AFP
@ninafawr tweets: Freedom of expression and free press are core democratic values in France. They cannot and will never be defeated. #LT #CharlieHebdo
The French president also says that "several terrorist attacks were thwarted in recent weeks".
President Hollande says it is a "terrorist attack" of "exceptional barbarity".
President Hollande speaks at the Charlie Hebdo offices, confirming the 11 deaths and four seriously wounded.
The assault happened late in the morning local time, when masked gunmen entered the building, and began shooting with automatic weapons - reports speak of up to 50 shots being fired.
Five of the 10 people injured are in a critical condition, police say.
The British Prime Minister, David Cameron, has tweeted to condemn the attack: "The murders in Paris are sickening. We stand with the French people in the fight against terror and defending the freedom of the press."
Ten people are wounded in the attack, police say.
During the shoot-out some of the magazine's staff took shelter on the roof of the building, the International Business Times reported.
This picture has been posted on social media from near the scene, showing bullet holes in a police vehicle.Copyright: @julienrbcc/PA Wire
A victim is evacuated on a stretcher after the attack on the Hebdo offices.Copyright: AFP
Paris has been put on maximum alert following the attack, officials say.
@Hellawyntweets: People who hate the press also hate freedom. They are absolutely crazy. Killing in the name of intolerance is shocking! #CharlieHebdo
The BBC's Lucy Williamson in Paris says that witnesses spoke of sustained gunfire at the Hebdo office as the attackers opened fire with Kalashnikov assault rifles.
Other French media outlets have been warned by police to be on alert and pay attention to security following shooting at Charlie Hebdo, BBC in Paris reports
Twelve people are killed in the attack, police say.
This was the scene near the Charlie Hebdo a short while ago.Copyright: AFP
President Francois Hollande is to visit the magazine's offices shortly, officials say.
Police official Luc Poignant says that it is a scene of "carnage" at the Hebdo offices.
@ImadMesdouatweets: #France press already making implicit links between #CharlieHebdo's Islamic caricature controversy and today's attack. Everyone chill: wait!
"About a half an hour ago two black-hooded men entered the building with Kalashnikovs (guns)," Benoit Bringer told France Info radio. "A few minutes later we heard lots of shots," he said, adding that men were then seen fleeing the building.
The offices of Charlie Hebdo have been attacked before. In 2011, they were petrol-bombed soon after naming the Prophet Muhammad as its "editor-in-chief" for its next issue.
Ten people are killed in the attack, Paris prosecutor says.
@lahnabeetweets: Chills down spine hearing #CharlieHebdo story, what is this permanence of attack of some sort or the other there.
Several people are reported to have been killed in the attack. French journalist Benoit Bringer who saw the attack told the iTele network he saw several masked men armed with machine guns, AFP news agency reports.
Welcome to the BBC's live coverage of the unfolding attack at the Paris offices of satirical magazine Charlie Hebdo.