Image source, PA

London Mayor Sadiq Khan has said his "message to those that want to harm us and destroy our way of life is: you won't succeed, you wont divide us, we won't be cowed by terrorists". 

Mr Khan, who attended this evening's Cobra meeting, said London had been one of the world's safest cities in recent years despite the ever-present terror threat. 

Following his statement to media, acting deputy commissioner Mark Rowley stated earlier the officer who was killed in the attack was armed.

It has now been confirmed by police that he was not armed.

Image source, Getty Images

The first minister of Scotland, Nicola Sturgeon, has sent her condolences to the people caught up in the "horrific incident" in Westminster.

She added that the decision to suspend proceedings in Holyrood was "absolutely the right one" as a mark of respect and solidarity with the people of London.

She said: "My thoughts, as I'm sure the thoughts of everybody in Scotland tonight, are with the people caught up in this dreadful event.

"My condolences in particular go to those who've lost loved ones.

"My thoughts are with those who sustained injuries and we all feel a sense of solidarity with the people of London tonight."

She said she has convened a meeting of the Scottish government's resilience committee to review the attack and any implications it may have for Scotland.

"It's important to stress that there is no intelligence of any risk to Scotland, but the police are ensuring that all precautionary steps are being taken," she said.

What we know so far after an armed man drove into pedestrians on Westminster Bridge then stabbed a police officer.

Brian Wheeler

Image source, EPA

A few locals chat to the reporters. The mood is calm and almost resigned.

"It was a matter of time I suppose," says one man. "I'm old enough to remember the IRA days. I remember them saying 'we only have to get lucky once'."

Father Giles Orton, a Church of England curate from Derbyshire, in London to shop for "ecclesiastical supplies", says he is "just shocked and saddened".

But he adds, we "should be grateful" that it had not been worse.

Read more from Brian here

• Four people, including an armed police officer and a man believed to be the attacker, have died in a terror attack near the Houses of Parliament
• The man stabbed the officer outside Parliament before being shot dead  
• Two victims were among several pedestrians hit by a car on Westminster Bridge, before it crashed

Read the latest story here

Prime Minister Theresa May, who chaired a Cobra meeting this evening, said the full details of the "sick and depraved terrorist attack" were still emerging. 

She confirmed there was one attacker and the UK's threat level of "severe" will not change.

There will be an update from the Metropolitan Police later this evening, she said.

"Our thoughts and prayers go out to all who have been affected," she said.

"Let me make it clear today... any attempt to defeat those values through violence is doomed to failure.

"Parliament will come together as normal... and Londoners will get up and go about their day as normal... they will walk these streets, they will live their lives... never giving into terror and never allowing the voices of hate and evil to drive us apart."

Prime Minister Theresa May is making a statement outside Downing Street. 

BBC Newsnight

Angie describes how she saw multiple bodies on the ground.

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Lights on the Eiffel Tower will be switched off at midnight in France (23:00 GMT) in solidarity with those killed and injured in the attack. 

The decision was taken by Paris Mayor Anne Hidalgo, who said in a statement that the two capitals "share a common love of freedom and an attachment to democracy" and were "tolerant and cosmopolitan cities, open to the world".

She also wished a swift recovery to the three French high school students injured in the attack.

Tony Kay, deputy head of mission at the British embassy in Israel, has tweeted a photo of Tel Aviv city hall lit up in the colours of the Union Jack.

Several Israeli politicians have also sent messages of support.

BBC Newsnight

An eyewitness to the Westminster attack, Ismail, describes what he saw to BBC Newsnight's  James Clayton.  

The Commons annunciator, which normally provides information about who is speaking inside the chamber, is calling for any witnesses or those with information about today's attack to go to Westminster Hall.