A terror suspect accused of deliberately crashing a car outside the Houses of Parliament was not known to the security services, Scotland Yard has said.
The man, in his late twenties, was arrested on suspicion of terror offences after the silver Ford Fiesta he was driving collided with cyclists and pedestrians before crashing into security barriers just before 7.40am on Tuesday.
The suspect, who is understood to be from the Birmingham area, is being held in custody at a south London police station.
Metropolitan Police counter-terrorism head Neil Basu said he is not co-operating.
“Given that this appears to be a deliberate act, the method and this being an iconic site, we are treating it as a terrorist incident and the investigation is being led by officers from the counter-terrorism command,” he told reporters.
“We have not formally identified him yet. On the details we have at the moment, we don’t believe this individual was known to MI5 or counter-terror police.”
The silver car can be seen driving along the road next to Parliament Square before moving to turn right towards Westminster Abbey in footage of the incident aired on BBC News.
As an ambulance passes the car on its right-hand side, the vehicle swerves left, crossing oncoming traffic and colliding with cyclists before entering a small road and crashing into a security barrier.
A police officer can be seen jumping another barrier that runs along the side of the road to get away.
Images posted to social media showed a man wearing a black puffer jacket being led away in handcuffs from the car as armed police officers swarmed the scene.
There was nobody else in the vehicle and no weapons were found, police said.
Mr Basu added no other suspects have been identified and there is “no intelligence at this time of further danger” to Londoners.
Two people were taken to hospital, while a third person with minor injuries was assessed at the scene, the London Ambulance Service (LAS) said.
One was discharged from St Thomas’ Hospital before midday, while a woman is being treated for serious but not life-threatening injuries at St Mary’s Hospital.
After a meeting of the Government’s emergency Cobra committee, Theresa May urged the country to come together and carry on as normal.
In a statement released by Downing Street, the Prime Minister praised the “formidable courage” and professionalism of the emergency services who “ran towards” danger.
She said: “The threat to the United Kingdom from terrorism remains severe.
“I would urge the public to remain vigilant but also to come together and carry on as normal, just as they did after the sickening attacks in Manchester and London last year.
“The twisted aim of the extremists is to use violence and terror to divide us. They will never succeed.”
Reacting to the suspected attack, US President Donald Trump said on Twitter: “These animals are crazy and must be dealt with through toughness and strength!”
Witnesses described the car ploughing through cyclists in what appeared to be a deliberate act.
Ewelina Ochab told the Press Association: “I think it looked intentional – the car drove at speed and towards the barriers.”
Geoffrey Woodman, a strategy consultant from Battersea, had stopped at the traffic lights by Parliament Square on his cycle to work when the car swerved into cyclists and towards the security barriers.
“I was getting off the bike and put my foot down, then there was a sound like tyres screeching,” he told PA.
“This car turned round to the left and swerved into the wrong lane of traffic and into the bank where all the cyclists wait.”
He said most people managed to jump off their bikes to safety but one woman who “seemed in some distress” was clipped by the bonnet of the car as it passed.
Mr Woodman said paramedics from a passing ambulance stopped to help before armed police arrived on the scene.
Cyclist James Maker, 30, of Chelmsford, Essex, passed the scene in Westminster minutes later and saw a woman injured on the ground and the car crashed into the barrier.
“I looked to the right-hand side and there was a cyclist on the floor, clearly injured,” he told PA.
“It was a woman, they were clearly quite injured, they weren’t moving and they were in the recovery position.”
Jason Williams, 45, from Kennington, was walking to work when he saw the crash.
“I saw a car going at high speed towards Parliament. It hit a bollard,” he told PA.
“It looked deliberate. It didn’t look like an accident. How do you do that by accident? It was a loud bang.”
Streets around Parliament Square, Millbank and Victoria Tower Gardens were cordoned off as police, ambulances and firefighters arrived.
Bus driver Victor Ogbomo, 49, passed the scene just after the crash.
“All I saw was the smoke coming out of a vehicle, a silver vehicle… I just stopped the bus,” he said.
“The police said we have to move back, then in less than five minutes the response team came.”
The Houses of Parliament are surrounded with 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.
Masood abandoned his car then stabbed and killed unarmed Pc Keith Palmer before he was shot by armed police in a courtyard outside Parliament.
The terrorist threat against the UK is seen as unprecedented.
The Prime Minister’s official spokesman said there were 676 live investigations being carried out by the security services and counter-terror police at the end of June, up from more than 500 in March.
Some 13 Islamist plots and four by far-right extremists have been foiled in the past 18 months, he added.
There are roughly 3,000 active “subjects of interest” at any one time – while there is also a wider pool of more than 20,000 individuals who have previously featured in probes whose threat must be kept under review.
Earlier this year, the Government unveiled a refreshed counter-terror strategy.
Under the blueprint, MI5 intelligence will be shared with bodies outside the security community in an attempt to stop suspects before attack plots can crystallise, while anti-terror laws are to be strengthened to allow earlier interventions.