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 14:52 · Samuel Osborne]

[22 March 2017 14:57 · Samuel Osborne]

[22 March 2017 14:59 · Samuel Osborne]

The Independent's deputy political editor Rob Merrick said: "Two men have been shot - one, presumably the assailant looked like he could be dead.

"The second, a police officer, was wounded but moving. I saw at least one man running towards the exit of New Palace Yard, underneath Big Ben.

"Police were shouting at him, presumably to stop and/or drop his weapon. I think I heard two shots.

"A police officer fell to the ground clutching his arm or shoulder.

[22 March 2017 15:00 · Samuel Osborne]

[22 March 2017 15:00 · Samuel Osborne]

[22 March 2017 15:01 · Samuel Osborne]

Two people were seen lying within Old Palace Yard, immediately outside Westminster Hall.

[22 March 2017 15:01 · Samuel Osborne]

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

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

[22 March 2017 15:02 · Samuel Osborne]

[22 March 2017 15:02 · Samuel Osborne]

Witness Don Brind told the Press Association he heard shots being fired and saw two people apparently injured on the ground.

Mr Brind, a researcher for MPs, said: "I heard some shouting and saw some running out of the corner of my eye and then a short time after that there was a shot. I looked and I saw a civilian on the ground, with somebody standing over him with what I assumed to be a gun.

"Then I looked and about 10 yards away, there was a yellow jacketed person on the ground, who appeared to be alive and talking."

He said he assumed the person in the high-visibility jacket was a police officer.

[22 March 2017 15:06 · Samuel Osborne]

To clarify earlier reports: A police officer been stabbed and an alleged assailant shot by armed police.