Scotland Yard on Tuesday said its counter-terrorism command was investigating a morning incident in which a man drove his auto into the barricades outside the houses of parliament in Westminster, injuring pedestrians and cyclists.
The driver of the silver Ford Fiesta was immediately arrested at the scene by police and held on "suspicion of terrorist offenses".
Another recording shows injured cyclists and pedestrians lying in the street in the immediate aftermath of the incident.
Basu said the suspect had not been formally identified, but was not believed to be known to security forces.
Three people sustained non-life-threatening injuries and were treated at the scene, with a man and a woman taken to hospital but discharged by Tuesday evening.
The area is in lockdown after armed police swarmed the scene on Tuesday morning (local time). Guns drawn, they surrounded the vehicle, arrested the driver and led him away in handcuffs. "There was a loud bang from the collision and a bit of smoke", Ewelina Ochab said.
She said: "I was walking on the other side of the road".
London Mayor Sadiq Khan said "all Londoners, like me, utterly condemn all acts of terrorism on our city". A police officer can be seen jumping over another barrier to get out of the way.More news: Russia Contributed To Charlottesville Rally Violence, GOP Lawmaker Claims
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The Houses of Parliament are surrounded with security barriers of steel and concrete.
Stefan Rousseau/ZUMA Press/NewscomIn the aftermath of a auto attack outside the Houses of Parliament in London, U.K. officials have proposed making the area a car-free zone.
In Tuesday's incident, the auto slammed into barriers that had been extended following the Westminster Bridge attack.
"I was told to move and started to run", he said.
"It looked deliberate. It didn't look like an accident", he said. "How do you do that by accident? Our thoughts and prayers are with the people who have been injured".
President Donald Trump tweeted about the incident too, slamming the "animals" behind it and demanding that it be met with "toughness and strength".
In March of 2017, four people died after Khalid Masood rammed a auto into a crowd on Westminister Bridge.