A police station in north London had to be evacuated after a car crashed into the building.
The crash happened in Edmonton shortly before 19:00 GMT on Wednesday. The man then left the car and tried to set fire to the road using petrol, police said.
Footage, posted on social media, showed a vehicle partially embedded in the entrance of the building.
A man, aged 45, has been arrested on suspicion of arson, affray and criminal damage. He remains in custody.
The Met Police said the incident was not being treated as terror-related.
Both the London Ambulance Service and London Fire Brigade were called to the crash on Fore Street.
Police said officers had been able to return to the station and nearby residents, who had been initially evacuated, were allowed home. No injuries have been reported.
Enfield Council leader Nesil Caliskan had earlier described the crash as a "major incident" and urged people to avoid the area.
Store manager Ogur Mazlum, 34, witnessed the moment the car crashed into the building.
His wife Serife Mazlum said: "He literally just walked out [of his shop] to just call me and see if everything's okay at home.
"Then he said I have to shut the phone quickly... that was when the car crashed into the front of the police station."
#Enfield— London 999 Feed (@999London) November 11, 2020
Met Police say at 6:58pm a vehicle collided with the station office at #Edmonton Police Station.
A man has been detained in connection with the incident.
The vehicle remains at the scene. Specialist officers are in attendance while it is examined.
Mrs Mazlum said her husband, who speaks limited English, saw the car had crashed through an exterior glass entrance to the police station and a man was trying to get through a second barrier.
"He was insisting on trying to get inside, but the glass door wouldn't break anymore so he couldn't get any closer," she added.
"Then he casually got out of the car with a tank of petrol. He poured it down from the car into the middle of the road and then he just set it on fire."
Video footage of the immediate aftermath shows police officers tackling the man and putting out the flames.
Mrs Mazlum said another man watching the scene from across the street ran to intervene after the driver had set the fuel alight.
"He pinned [the driver] to the ground just as the police was arriving," she added.
"So by the time the police came and got out of the cars the citizen had already slammed him to the ground."
London Mayor Sadiq Khan said he had been in "constant contact" with Metropolitan Police Commissioner Cressida Dick about the incident.
Writing on Twitter, he said: "I'm grateful to the police officers and other emergency services who brought the situation under control and continue to investigate the incident."