Police are treating this as an act of terrorism.A man has been arrested on suspicion of terrorism offences after a car crashed outside the Houses of Parliament.
The vehicle swerved into cyclists and pedestrians shortly after 07:30 BST, injuring three people.
The suspect, in his late 20s, is not believed to be known to MI5 or counter-terrorism police, and is not co-operating with officers.
A woman is being treated in hospital for serious but non life-threatening injuries.
Scotland Yard's head of counter terrorism Neil Basu said: "Given that this appears to be a deliberate act, the method and this being an iconic site, we are treating it as a terrorist incident."
He added there was "no intelligence at this time of further danger" to London or the UK as a whole.
Sky sources: The suspect is not known to security services but is known to police in the midlands, where he is from. The car used was registered in Nottingham.