A young woman has died after she was hit by a marked police car responding to a 999 emergency call.
Witnesses said the 25-year-old pedestrian was crossing the road when she was struck and thrown into the air at about 11.20pm on Wednesday.
When the police car came to a stop, two officers jumped out and tried to save the woman, a witness said.
Paramedics soon arrived and attempted to resuscitate her before she was pronounced dead at the scene in Lambeth, south-west London.
The Metropolitan Police said the incident had been referred to the Directorate of Professional Standards and the Independent Office for Police Conduct (IOPC), which is now carrying out an independent investigation.
Witness David Chitidze, 25, said he was smoking on the balcony of his fourth-floor flat when he noticed a police car approaching with its lights and sirens activated.
The woman was crossing the road about 20 yards from a traffic light, he added.
David said: “The police vehicle was heading towards Brixton with sirens on and travelling at a very high speed, no traffic.
“There is a small bend around the corner and I saw the girl starting to cross and my heart dropped.
“She froze on the spot as the police car completely took her out and sent her flying. It all happened so quickly.
“Both the driver and passenger – policemen – instantly got out and began reviving her. She was unresponsive on the floor.
“The officers both reacted quickly. The driver in particular was distraught, I could tell.
“They were trying to bring her back. Many neighbours called the ambulance straight away. It was heartbreaking.”
A London Ambulance Service spokesperson said: “We were called at 11.22pm on Wednesday 9 June to reports of a road traffic collision in Stockwell Road, SW9.
“We sent two ambulances, a medic in a response car, an incident response officer and London’s Air Ambulance to the scene.
“Sadly, despite our efforts a woman was pronounced dead at the scene.”