Picture of scene outside Parliamentpublished at 16:59 Greenwich Mean Time 22 March 2017

Man, 75, who died in Westminster attack is named as Leslie Rhodes, from Clapham, London
Westminster attacker Khalid Masood, 52, was originally called Adrian Russell Elms
Masood spent two years teaching English in Saudia Arabia between 2005-2009
Four people are still being questioned by police, six have been released
Fifty people hurt in attack, two in critical condition, one has life-threatening injuries
Prince Charles visits attack victims at King's College Hospital in London
Paul Gribben, Kate Palmer and Marie Jackson
BBC News Channel
Latest pictures show people being supervised as they are allowed to leave the Palace of Westminster.
The BBC's Daniel Sandford says the Met's statement was very interesting and that although the details are "very sketchy" at this stage, it is clear the police are treating it as a terror attack.
Prime Minister Theresa May will chair a meeting of the Government's emergency Cobra committee later today, a Downing Street spokesman said.
It appears that the Met's current acting commissioner Craig Mackie was an eye-witness to the incident as he was in the area at the time. He is not injured but could provide absolutely vital testimony.
Anyone with information about the incident is urged to call 0800 789 321. He also says anyone who sees anything suspcious which they believes constitutes an emergency should call 999.
Asked whether the incident is over, the officer says he cannot speculate but his focus is on keeping London safe.
He says there are a number of casualties but he cannot confirm the number or the nature of injuries.
Met commander BJ Harrington is making a statement. He says although he is "open-minded" to the motives, it is being treated as a terrorist incident.
Peer and former police officer Lord Paddick says he understands there was a suspect package attached to a vehicle outside Parliament and this is the reason the building has not been evacuated.
He says the loss of life is a tragedy but "great credit" is due to the police that no one inside the Palace of Westminster appears to be in danger at the moment.
He says the situation is "calm" with people "relatively relaxed".
Mayor of London, Sadiq Khan, has issued a statement: “There has been a serious incident near to Parliament Square this afternoon which is being treated as a terrorist attack until the police know otherwise.
"I have spoken to the Acting Commissioner. The Metropolitan Police Service is dealing with the incident and an urgent investigation is underway. My thoughts are with those affected and their families.
“I would like to express my thanks to the police and emergency services who work so hard to keep us safe and show tremendous bravery in exceptionally difficult circumstances. For the latest information please visit news.met.police.uk, external .”
The BBC's political editor Laura Kuenssberg, who is in Parliament, says it is a "very tense" situation there with people told they cannot leave.
"It is clearly a very dangerous situation," she says.
She says there are unconfirmed reports of bomb squad officers now inside Parliament and the military on the streets outside.
There are also reports, she adds, that other government departments are in lockdown but makes clear she cannot confirm this.
The BBC's Wyre Davies says the London Eye has been stopped and that people who were inside the capsules at the time of the incident are being held there.
BBC Newsnight presenter Evan Davis describes what he saw at Westminster.
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The Metropolitan Police are due to make a statement in about 15 minutes time, BBC News understands.
Labour MP Jon Ashworth says he and his fellow MPs are in a state of "absolute shock" at what has happened.
He says it was the busiest day of the week, due to Prime Minister's Questions, and Parliament was full of visitors.
Quote MessageIt's a very busy building and it's a very open building. But generally anybody who wants to come and see their MP can come and see their MP and that's a good thing about democracy but today has really brought all that into focus."
We know that Theresa May is now back in Downing Street and that other senior ministers are still in Parliament.
The home secretary and foreign secretary are not among them since Amber Rudd is currently on a trip to Pakistan while Boris Johnson is in Washington for talks with his counterpart.
BBC Wales tweets news from Cardiff Bay's presiding officer.
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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.
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Matt Haikin, 44, from London, said he was in shock after seeing the aftermath of the crash on the bridge.
He said: "I just saw a car that had clearly driven off the road into the fence outside Parliament.
"As I went past I noticed there was a body next to it and quite a lot of blood and people standing around.
"Fairly shortly after I heard some shots, at which point it was clear it wasn't just an accident, something else was going on."
He then moved to look through the Palace of Westminster gates and saw "a lot of people, people in uniform, I think I saw a couple of bodies on the ground, I couldn't tell you if they'd been asked to lie down or if they were injured".
Sir Roger Gale, MP for North Thanet, tells BBC Radio Kent about what happened.
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