A woman has been taken to hospital after being hit by a marked police car.
The Met Police vehicle struck the pedestrian, in her 20s, on Warwick Road, near the junction with Kensington High Street in west London, at about 21:55 BST on Tuesday.
She was treated at the scene before being taken to a central London hospital where she remains in a critical condition.
It is not known whether the police car was responding to an emergency call.
Road closures have been put in place in the area and an investigation is under way.
Scotland Yard said the Directorate of Professionals Standards had been informed and the Independent Office for Police Conduct has launched an investigation.