London attack as it happened: Five dead and 40 injured after terror incident in Westminster

Westminster terror attack: Timeline of events

A police officer has been stabbed and an alleged assailant shot by armed police outside the Houses of Parliament.

Here's what we know so far:

• Police officer died after being stabbed outside Parliament
• Two people reported dead after a car ploughed into crowd on Westminster bridge causing multiple casualties
• Metropolitan police are treating this as a terrorist incident
• Eyewitness account of the stabbing incident outside Parliament gate
• Donald Trump has been briefed on the attack, Sean Spicer confirms
• Theresa May was '40 yards away' from scene of stabbing, was immediately evacuated and confirmed safe
• House of Commons session suspended and MPs evacuated

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Commons Leader David Lidington has told MPs a "police officer has been stabbed" and the "alleged assailant was shot by armed police" following a "serious" incident within the parliamentary estate.

Minutes later, an emergency services helicopter landed in Parliament Square, as sirens were heard outside.

Iframe:

Air ambulance medics came from the helicopter to assist the casualties.

A woman was confirmed dead after a car ploughed into corwds on Westminster Bridge causing multiple casualties (Reuters)

Two people lay on the ground in the yard. One of them appeared to have had clothes removed as emergency workers attempted to resuscitate the pair.

Parliament Square was closed to traffic.

[22 March 2017 15:22 · Samuel Osborne]

Our corespondent Lizzie Dearden is making her way to Westminster.

She says people are calm despite multiple helicopters flying overhead. 

[22 March 2017 15:23 · Samuel Osborne]

[22 March 2017 15:24 · Samuel Osborne]

A witness, who was in the Commons for a job interview, told The Independent: "I was about to leave out of Westminster Hall then loads of people came through screaming."

He said they were tourists and are now being held in the Central Lobby.

[22 March 2017 15:26 · Lizzie Dearden]

I'm in Westminster, where the air ambulance is has landed in Parliament square. Crowds pushed back more than 100m from bridge http://pbs.twimg.com/media/C7iEpl7W0AAKPor.jpg

[22 March 2017 15:27 · Lizzie Dearden]

Police now pushing people back further from Paliament Square 'for their own safety'

[22 March 2017 15:27 · Samuel Osborne]

Eyewitness video has shown five people being "mown down" by a car on Westminster Bridge.

Radoslaw Sikorski posted a video to Twitter purporting to show people lying injured in the road on Westminster Bridge.

Mr Sikorski, a senior fellow at Harvard Centre for European Studies, said he saw at least five people lying on the ground after being "mown down" by a car.

"I heard what I thought what I thought was just a collision and then I looked through the window of the taxi and someone down, obviously in great distress," he told the BBC.

"Then I saw a second person down, and I started filming, then I saw three more people down, one of them bleeding profusely."

[22 March 2017 15:29 · Jon Stone]

In a pub in Westminster charging my phone - everyone watching the news

[22 March 2017 15:31 · Sarah Sanders]

.@POTUS has been briefed on the situation in the U.K. Continuing to monitor and update

[22 March 2017 15:31 · Chris Green]

Deputy Presiding Officer Linda Fabiani says security at Holyrood is "under review" in light of Westminster incident

[22 March 2017 15:32 · Andrew Griffin]

 Kevin Schofield, the editor of PoliticsHome.com heard "a very loud bang" from the press gallery inside the Houses of Parliament followed by lots of shouting and men running around.

He initially thought it was a car crash but then he looked outside the window to a heavily-guarded area outside which is out of bounds to the public.

He told Sky News: "Someone rushed through, attacked a policeman, a policeman went down, another policeman came and he was rescued.

"The man who had assaulted him got up and he appeared to be carrying either a knife or a gun. Then we heard gunfire, lots of gunfire, maybe five or six rounds.

"All I remember seeing is the man approaching the police officer probably with a knife and then there was gunfire.

"He was walking towards a second policeman with his arm outstretched, with what looked like a knife in his hand, having already assaulted another policeman.

"It was at that moment that you realised that something serious was happening - a man had broken in to Parliament and had a weapon."