There were two car bombs found and defused in London yesterday, which I didn't see mentioned here. This sounds like it might have been the result of an accident that got that press because of heightened security, but that's not confirmed.
eye witnesses say cannisters were involved and the driver was full speed towards the building...looks like terrorists.
UK Government spokesman just said the incident is not being treated as a national security threat, so not sure what they think it was.
BBC:
Eye-witness Richard Gray told BBC News 24: "A green Jeep was in the middle of the doorway burning.
"There was an Asian guy who was pulled out of the car by two police officers, who he was trying to fight off. They've got him on the ground.
"The car didn't actually explode. There were a few pops and bangs which presumably was the petrol."