A police dog team works behind the cordon around Parliament Square after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Armed police stand in the street after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

A car that crashed outside the Houses of Parliament is surrounded by members of the emergency services in Westminster, London, Britain, August 14, 2018.

Police officers stand at a cordon after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Armed police officers stand at a cordon after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Police officers stand at a cordon after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Assistant Commissioner of the Metropolitan Police Neil Basu speaks to the media after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Police officers stand at a cordon after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018. REUTERS/Hannah McKay

Assistant Commissioner of the Metropolitan Police Neil Basu speaks to the media after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Armed police stand in the street after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

A forensics investigator arrives at the scene after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.

Police officers stand at a cordon after a car crashed outside the Houses of Parliament in Westminster, London, Britain, August 14, 2018.