Footage posted to social media showed a man appearing to exit the crashed vehicle, before walking into the road pouring a flammable liquid.
The man then lit a strip of fire across an entire lane, directly in front of two buses.
A police car arrived just as the man ignited the liquid and an officer appeared to quickly detain him.
“At around 18:58 on Wednesday, 11 November a vehicle collided with the station office at Edmonton Police Station,” Scotland Yard said in a statement.
“A man – no further details – has been detained in connection with the incident. The vehicle remains at the scene. Specialist officers are in attendance while it is examined.