What we know:

• A man has been arrested on suspicion of terrorism offences after a car crashed outside the Houses of Parliament
• The suspect, in his late 20s, is not co-operating with police
• No-one else was in the car and no weapons have been found
• The BBC understands the suspect is from the Birmingham area
• One woman is being treated in hospital for serious but non life-threatening injuries
• Westminster Tube station and Parliament Square have reopened

Our main story will continue to be updated. Read more here.

International security expert Will Geddes says the latest incident in Westminster raises questions over whether the area around the Houses of Parliament should be pedestrianised.

It has been 18 months since Khalid Masood ploughed a car into crowds on Westminster Bridge, killing four people.

Mr Geddes told the BBC that counter terrorism initiatives often come off the back of these types of incidents.

He said: "There are some very good questions to be put forward as to whether this area in fact probably needs to be pedestrianised."

"Bearing in mind its iconic position, maybe more steps need to be taken."

Damaged bicycles were left leaning against the wall outside Parliament that was at the scene of the crash this morning.

The car swerved into cyclists and pedestrians before it hit security barriers shortly after 07:30 BST.

Image source, Reuters

Image source, Reuters

Scotland Yard is asking anyone with information on the crash to call 0800 789 321.

Anyone with video or pictures of the incident is asked to send them to police, external.

Frank Gardner
BBC Security Correspondent

BBC Security correspondent Frank Gardner says he doesn't expect it to take long for the police to gather information on the suspect.

He says: "We live in a digital age, there are no secrets.

"It'll be out pretty soon what he's been up to, who he's been communicating with, where he's been going, what he's been doing, what he had for breakfast, frankly."

Earlier, the Met Police said the suspect was not co-operating with police and had not yet been formally identified.

• At 07:37 BST a silver Ford Fiesta hatchback crashed into barriers outside Parliament in central London

• The driver, a man in his late 20s, has been arrested on suspicion of terrorist offences and is being held at a south London police station
• Two people were taken to hospital. A woman is being treated for serious but not life-threatening injuries, while a man has since been discharged
• Metropolitan Police Assistant Commissioner Neil Basu said the suspect was not co-operating with police and had not yet been formally identified
• BBC home affairs correspondent Daniel Sandford says sources have told him the suspect is from the Birmingham area
• There was nobody else in the vehicle and no weapons have so far been found
• A meeting of the government's emergency committee, Cobra, is currently being held. No cabinet ministers are expected to attend

Cameras caught the aftermath of this morning's crash as officers responded to the incident in Westminster.

More pictures are coming in from the scene in Westminster of forensic officers examining the silver Ford Fiesta.

Image source, Reuters

Image source, PA

The Mayor of London, Sadiq Khan, says people will see more armed and unarmed police officers on the capital's streets over the course of today and the next few days.

He said members of the public "shouldn't be scared by that".

"They should remain calm and vigilant," he said.

Nickie Aiken, leader of Westminster City Council, said: “Our thoughts are with those hurt and our thanks to the brilliant emergency services who were so quickly at the scene.

“The House of Commons was targeted again today – as it was last year – but our democracy, and our way of life, will continue to defy those who try to undermine it.

“The safety of the people who live, work and visit in Westminster remains our priority and we will work to ensure our capital remains a welcoming city.”

The government will hold a meeting of its emergency committee, Cobra, at 14:00 BST to discuss the incident.

Prime Minister Theresa May earlier tweeted that her thoughts were with those injured and thanked the emergency services for their "immediate and courageous" response.

BBC home affairs correspondent Daniel Sandford says sources have told him the suspect arrested on suspicion of terrorism offences is from the Birmingham area.

He adds that the suspect was not known to MI5 or the counter terrorism network, but was known to police.

The man, believed to be in his late 20s, was seen being detained by police at the scene.

Parliament says the "safety and security of those working in or visiting the UK Parliament is our top priority".

In a statement, external following this morning's incident, it said: "Our current measures are robust and are continuously reviewed.

"Entrances and exits to the Parliamentary Estate are currently closed due a police cordon, with the exception of Portcullis House."

Image source, PA

Image source, PA

The Houses of Parliament are surrounded by security barriers of steel and concrete.

The measures were extended in the wake of the Westminster Bridge attack in March 2017, when Khalid Masood ploughed a car into crowds on Westminster Bridge, killing four people.