Brian Wheeler

The roads around the Houses of Parliament are choked with traffic and tourists at the best of times but on Wednesday there is an extra buzz about the place for Prime Minister's Questions at midday.

It is the best day to see your MP, as they are nearly all in the building. Queues to get into Parliament start forming early in the morning. The protests in Parliament Square seem noisier and more colourful than normal.

Things start to wind down after the main event but there is still a festive atmosphere in the pubs next to Parliament, as people from all parts of the UK - down in London for the day to lobby their MPs - swap stories and buy drinks.

Now the wide roads leading in all directions to the Houses of Parliament are silent and empty, blocked off by police tape, following a deadly terror attack. The police cordon covers an area of a few square miles and keeps being extended.

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Image source, AFP

White House spokesman Sean Spicer has told reporters: "We obviously condemn today's attack in Westminster which the United Kingdom is treating as an act of terrorism. 

"And we applaud the quick response that the British police and their first responders made to the situation. 

"The victims in this are in our thoughts and our prayers. The city of London and Her Majesty's government have the full support of the US government in responding to the attack and bringing those to justice who are responsible."

BBC Radio 5 live

Christopher Hope, chief political correspondent for the Telegraph, tells BBC Radio 5 Live: "You can’t see the full picture when you are in the middle of it, as we are.

"We will be back here [tomorrow] - we are not going to let anyone win on this.

"What happens tomorrow I don’t know - they are going to have to have a complete overhaul to security here."

Prime Minister Theresa May has ordered flags to be lowered to half-mast over Downing Street as a mark of respect to the innocent people who lost their lives. 

The announcement comes as she chairs a meeting of the government's emergency Cobra committee.

The Cobra committee brings together government ministers with senior officials of the emergency services and security and intelligence agencies.

BBC Newsnight

Here are some more scenes from Westminster earlier this afternoon - including a police cordon and helicopter. 

Footage shot by BBC Newsnight presenter Evan Davis.

It's emerged that the first doctor on the scene of the Westminster attack was the current chairman of the junior doctors' committee at the British Medical Association.

Dr Jeeves Wijesuriya was at Westminster talking to a regional BBC team, when the events started unfolding.

He tried to resuscitate both the police officer and the assailant, and worked with paramedics in the ambulance on the way to hospital.

He told the BBC: "I saw the screaming and ran to help.

"The police got me in to help at the scene.

"We gave the officer cardiac massage and spent 52 minutes trying to resuscitate the other man.

"We did everything we could, in terms of basic life support and starting to triage injured people at the scene."

BBC Newsnight

BBC Newsnight presenter Evan Davis describes what he saw and heard at Westminster.

Dominic Casciani
Home Affairs Correspondent

BBC home affairs correspondent Dominic Casciani tells BBC Radio 5 Live: "To be frank it was probably only a matter of time before it happened."

He said the police "will be throwing everything" into the investigation.

"We thought there were two [attackers] now they believe it is only one," he said.

"It is a massive [police] operation."

BBC Radio 5 live

On the scene in Westminster, Emma Barnett, for BBC Radio 5 Live, says: "On Whitehall at the moment the foreign media press has descended.

"The world is looking at London right now, they are looking at how exactly we are responding and exactly how the city is responding."

Scottish First Minister Nicola Sturgeon says her thoughts are with everyone caught up in the "dreadful" incident at Westminster, including the emergency services.

She said she supported the decision to suspend the Scottish Parliament.

Home Secretary Amber Rudd has just made this statement:

"We do not yet know the full impact of this terrible incident. But I know that the whole country will be thinking and praying for those who are affected, as I am. 

"I want to thank the emergency services for the quick response and pay tribute to their bravery, their courage and their professionalism. 

"I have been briefed by the Met Police and by the security services and the security minister has also been updated. 

"This is an ongoing incident and the government will continue to be updated. The prime minister will chair COBRA today. 

"The government's top priority is the security of its people and I urge everyone to remain calm but to be vigilant and if they see anything they are concerned about they should report it to the police. 

"We have the best police, the best security services in the world and we must make sure that we let them get on with doing their job. 

"The British people will be united in working together to defeat those who would harm our shared values. Values of democracy, tolerance and the rule of law. Values symbolised by the Houses of Parliament. Values that will never be destroyed."

BBC Radio 5 live

Emma Barnett, for BBC Radio 5 Live, says the streets around Westminster are unsually quiet.

It is "extremely eerie", she says, "essentially its [London's] heart has stopped beating".