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- Parliament suspended following terror incident
Four people, including a police officer and an attacker, are dead and 40 others have been injured in a terror attack in Westminster.
Updates on the terror incident at the Houses of Parliament will be continuing on the BBC live page: Westminster attack - latest updates.
Click on that link for unfolding news, which will continue there from our BBC colleagues.
A BBC reporter has tweeted the video of the statement made by Holyrood's presiding officer Ken Macintosh earlier as the Scottish Parliament suspended its debate on independence for the day.
BBC Live reporter
The Green MP for Brighton Pavilion is one of those locked in the Chamber of the Commons, while the security incident is dealt with.
We were all in the process of voting when the doors were closed and we were told to get come into the main Chamber. It does feel very surreal to be honest and my heart goes out to all those involved. We live in difficult times and I just hope that people keep calm.'
The House of Commons and House of Lords have adjourned for today.
The annunciators - which deliver information for staff around the Palace of Westminster - advise staff to remain in their offices, while armed firearms officers carry out a sweep of the estate.
The building is in lockdown, they say.
- A policeman has been stabbed and his attacker shot by officers at the House of Parliament
- Police are treating it as a "terrorist incident"
- The attacker is reported to have mowed down several pedestrians as he drove a grey Hyundai car across Westminster Bridge before crashing it into railings
- He is then reported to have run through the gates of the Palace of Westminster and stabbed the officer
- Eyewitnesses said he was shot by police as he approached a second officer clutching his knife
- House of Commons and Lords in lockdown - as is nearby St Thomas's hospital
- Public urged to avoid the area and Westminster Underground station is closed
- Prime Minister Theresa May was seen being ushered into a silver Jaguar in the grounds of the Palace of Westminster as what sounded like gunfire rang out at around 14:45 GMT
- A Downing Street source confirmed the prime minster was "OK".
Holyrood suspends its sitting today, following news of the terror incident in Westminster.
The Scottish Parliament was debating the proposal for a second independence referendum, with a vote due at 5.30pm.
The police confirm a firearms incident on Westminster Bridge Road at 1440 GMT.
Downing Street say the prime minister is "safe".
A car has crashed in to the perimeter at Parliament on Westminster Bridge Road.
Commons leader David Lidington says a man attacked a police officer at Parliament and has been shot by police.
The House of Commons and Lords suspended until further notice.
House of Lords
The House of Lords were just about to begin their regular afternoon session when the security incident occurred.
The Parliamentary annunciator system is now advising everyone in the building to "remain in their offices while armed officers conduct a sweep of the estate".
House of Commons
Commons Leader David Lidington has just announced that business in the Commons will be suspended for the rest of the day:
"I hope the House would agree that in the current circumstances it would not be right to continue with the day's business."
The business will be re-scheduled for a mutually convenient date, he says.
With that, Deputy Speaker Lindsay Hoyle adjourns the Commons, promising to keep MPs informed.
Prime Minister Theresa May was seen being ushered into a silver Jaguar car as what sounded like gunfire rang out at Parliament during the incident.
A Downing Street source confirmed that Prime Minister Theresa May was "OK".
The moment the House was suspended following reports of shots fired close to the Houses of Parliament in central London.
House of Commons
Leader of the House David Lidington returns to the House to tell MPs that the House is still in lockdown.
He says it is not right to continue with today's business and discussions will take place to reschedule the day's bills and debates.
House of Commons
At 14.45 Deputy Speaker Lindsay Hoyle suspended the sitting of the Commons during a vote on the Pension Schemes Bill. He gave no further reason for the suspension at this point.
At 15.00 Leader of the House David Lidington gave a statement to MPs on events:
"There has been a serious incident within the estate, it seems that a police officer has been stabbed and that the alleged assailant was shot by police and an air ambulance is at the scene attending to the casualties.
"There are also reports of further violent incidents in the vicinity of the Palace of Westminster, but I hope that colleagues will appreciate that it would be wrong of me to go into further details until we have confirmation from the police and from the House security authorities on what is going on.
"I shall endeavour to do the best I can at the Despatch Box and by communicating with my opposite numbers in political parties to ensure that members are kept aware of what is happening.
"At the moment the very clear advice from the police and the director of security in the house is that we should remain under suspension and that the chamber should remain in lockdown until we receive advice that it is safe to go back to normal procedures."
Press Association reporter Laura Harding, who was in Westminster at the time of the incident, said:
"Everyone has been evacuated into Central Lobby, including a group of schoolchildren and kitchen staff.
"Around 15 schoolchildren aged around 10, with armed police coming through the lobby now.
"The children are really calm, the teachers are comforting them.
"Everyone is standing around on their phones.
"There are also a bunch of young people from the Hammersmith Boxing Club in their tracksuits and the British Lionhearts boxing group."
Shots are reported to have been fired close to the Houses of Parliament in central London.
Politicians and journalists have tweeted about hearing loud crashes outside the buildings,
Witnesses said they saw people being treated for wounds and reported seeing a man with a knife in the grounds.
Staff inside Parliament were told to stay inside their offices. The BBC's Laura Kuenssberg said police told her someone had been shot.
Scotland Yard said it was called to a firearms incident on Westminster Bridge amid reports of several people injured.
Transport for London said Westminster underground station has been shut at the police's request.
House of Commons
Leader of the House David Lidington's statement to MPs relates the advice from the police.
"The very clear advice from the police is that we should remain in lockdown until it is safe to return to normal procedures," he says.
Shadow Leader of the House Valerie Vaz rises to thank the police and staff for keeping MPs safe.
Deputy Speaker Lindsay Hoyle suspends the sitting until further notice.
The Commons is hearing a statement from Leader of the House David Lidington that the House is suspended, amid reports of a violent incident.
The Houses of Parliament annunciator system is now reporting that the sitting of both Houses of Parliament will remain suspended "until a time indicated by the annunciator."
Scotland Yard has said it was called to a firearms incident on Westminster Bridge, outside the Houses of Parliament, amid reports of several people injured.
An air ambulance has landed in Parliament Square.
The Press Association reports that two people were seen lying within Old Palace Yard, immediately outside Westminster Hall.
The sitting inside Parliament has been suspended.
Two people shot outside Parliament and building on lockdown, a parliamentary official tells Reuters.