Armed police descended on a car park close to the House of Lords entrance where a vehicle crashed into a security barrier early on Tuesday morning. One man has been arrested, Scotland Yard said.
Smoke could be seen coming from the scene.
According to Metro newspaper, a police officer can be heard in a video from the scene saying that pedestrians may have been hit prior to the collision, and a witness said that several cyclists were hit.
There have been no confirmed reports of any casualties at this time. Parliament is currently in recess.
