Denmark is on high alert after a gunman in Copenhagen killed one person and injured three at a free speech debate attended by a Swedish cartoonist.
Several dozen shots were fired at the seminar and a manhunt is now under way.
Prime Minister Helle Thorning-Schmidt described it as a "politically motivated" act of terrorism.
Cartoonist Lars Vilks, who has faced death threats over his caricatures of the Prophet Muhammad, was unhurt.
He told the Associated Press news agency that he believed he was the intended target of the attack.
"I'm not shaken at all by this incident," he added. "Not the least.''
Police had initially thought there were two suspects, but later said they were searching for a lone gunman.
They released photographs showing the alleged attacker apparently wearing a purple balaclava and thick puffer jacket.
The three injured were police officers.
An audio recording, obtained exclusively by the BBC, revealed the moments leading up to the attack.
One of the speakers at the debate, which took place at a cafe and concerned the limits of free speech, is suddenly interrupted by a barrage of gunshots.
Speaking to the BBC, eyewitness Dennis Myhoff-Brink said: "People were trying to get to the doors, trying to get out of the room, hiding between or behind the tables and chairs, and some people were running out into the street."
The French ambassador, Francois Zimeray, was also present during the attack.
Shortly after the shooting, a message appeared on his Twitter feed saying he was still alive.
The area around the venue is under lockdown, reports the BBC's Malcolm Brabant, and police have erected cordons as they search a nearby park.
Officials said the gunman made his getaway by car. A black Volkswagen Polo was later found abandoned a short distance away from the scene, police said.
On a personal website of Lars Vilks, the debate was described as a talk on whether any limits should be placed on artistic expression or freedom of speech.
A description of the event asked whether artists could "dare" to be blasphemous in the wake of attacks by Islamist gunmen in Paris last month against satirical magazine Charlie Hebdo.
In an indication of the threat faced by the cartoonist, a note was included on the website saying there was always "strict security" whenever he spoke in public.
An organiser of Saturday's event, Helle Merete Brix, told BBC World TV it was being guarded by armed police and security agents from the Danish intelligence service, as well as Mr Vilks' own bodyguards.
She described what happened in the moments after the attack.
"We were in a room just Lars and me with a couple of security guards," she told the BBC. "We were trying to keep up our good spirits, holding hands and saying to each other, it's going to be OK."
Lars Vilks stoked controversy in 2007 by drawing pictures of the Prophet Muhammad dressed as a dog.
In 2010 two brothers tried to burn down the cartoonist's house in southern Sweden and were imprisoned for attempted arson.
Lars Vilks: A controversial career
June 1946: born in Helsingborg, Sweden
2007: Stoked controversy when he drew a series of cartoons depicting the Prophet Muhammad as a dog which were published in a number of Swedish papers
Sept 2007: $100,000 bounty placed on his head by then leader of al-Qaeda in Iraq
March 2010: Seven Irish citizens arrested over separate plots to kill Vilks: US woman Colleen LaRose, aka Jihad Jane, also arrested and later jailed for 10 years for conspiracy to commit murder
May 2010: Assaulted by Muslim protesters during a lecture about free speech at Uppsala University, Sweden
Sept 2011: Three men arrested in Gothenburg, Sweden, for plotting to kill Vilks
March 2013: Placed on "most wanted" list By al-Qaeda in the Arabian Peninsula
Feb 2015: Gunmen attack event on blasphemy, art and freedom of expression organised by Vilks at the Krudttoenden café in Copenhagen, Denmark
Satirists targeting Islam have been in the spotlight since the January attacks in France, when 17 people were killed in separate incidents over a three-day period.
Following Saturday's incident in Copenhagen, a columnist for Charlie Hebdo who narrowly escaped the Paris shootings said it was necessary to "fight fascism at all costs", reported the AFP news agency.
"We are all Danish tonight," added Patrick Pelloux, adapting a slogan used about Charlie Hebdo following the Paris attacks.
A message from French President Francois Hollande's official Twitter feed expressed solidarity with Denmark's prime minister.
Cartoons depicting the Prophet Muhammad were published by a Danish newspaper in 2005, sparking deadly riots in some Muslim countries.
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