LONDON: In a terror attack, a speeding car crashed into security barriers outside the UK's Parliament during rush hour, injuring three persons, Scotland Yard said as a man was arrested on suspicion of terrorism offences.
Scotland Yard's Counter-Terrorism Command is treating the incident in central London as a terrorist attack.
The man, in his late 20s, has been arrested on suspicion of terrorism offences.
Metropolitan Police Assistant Commissioner Neil Basu, the Indian-origin National Lead for Counter-Terrorism Policing in the UK, said the man was not cooperating with police as they work to establish his identity.
"Our priority is to formally establish the identity of the suspect and his motivation if we can. He is not currently cooperating," Basu said, adding that the suspect was not known to security services or under surveillance.
"There is no intelligence at this time of further danger to Londoners or to the rest of the UK connected to this incident."
"Given that this appears to be a deliberate attack, the method and this being an iconic site, we are treating it as a terrorist incident," he said.
A Met police spokesperson said that there was nobody else in the vehicle, which remains at the scene and is being searched.
No weapons have been recovered at this stage.
Police have put up a Terrorism Act cordon, a reaction to incidents of this nature near any high-security hotspots in the city.
"At 0737 hrs (1207 IST) today, a car was in collision with barriers outside the Houses of Parliament," the Met Police said.
The car was seen wedged into flap-style barriers that allow vehicles access to the House of Lords, giving the impression that the driver may have been trying to gain access to the Parliament building.
Prime Minister Theresa May said: "My thoughts are with those injured in the incident in Westminster and my thanks to the emergency services for their immediate and courageous response."
Home Secretary Sajid Javid also thanked emergency services for their quick response.
Mayor of London Sadiq Khan said he was in close contact with police.
London Ambulance Service said in a statement that it had "treated two people at the scene for injuries that are not believed to be serious and have taken them to hospital".
A total of three persons have been injured.
The area around Parliament Square has been cordoned off as investigations continue.
The incident occurred at peak rush hour, resulting in major travel disruptions as Westminster tube station was shut down and road closures put in place.
Streets around Millbank, Parliament Square and Victoria Tower Gardens have been cordoned off.
Heavy armed police presence could be seen in the area as the incident unfolded.
Barry Williams, a BBC member of staff, said: "I heard lots of screams and turned round".
"The car went onto the wrong side of the road to where cyclists were waiting at lights and ploughed into them.
Then it swerved back across the road and accelerated as fast as possible and hit the barrier at full pelt.
"It was a small silver car and he hit it at such speed the car actually lifted off the ground and bounced," Williams said.
Some eyewitnesses reported seeing smoke emanating from the hood of the car.
The Houses of Parliament are surrounded with security barriers of steel and concrete.
Parliament is currently not sitting.
The ongoing parliamentary recess period meant there would have been no Members of Parliament (MPs) or peers in the Houses of Parliament or on their way into the building.
However, hundreds of workers and officials would have been within the complex, including construction crew involved in refurbishment work on the Palace of Westminster, which houses the iconic Big Ben.
Britain's terror threat level remains at "severe", which means an attack is highly likely, since a series of terrorist attacks last year.
The UK has been on high alert since the March 2017 attack near Parliament, which was followed by a suicide bombing at an Ariana Grande concert in Manchester in May, which claimed 23 lives.
In June last year, a group of three ISIS-inspired men rammed a vehicle into pedestrians in London Bridge area before going on a stabbing frenzy, killing eight people before being shot by armed officers.