By Thomas Mackintosh, Ellie Price & Emily Atkinson for BBC
Lessar Avenue in the London suburb of Clapham (file image). Photo: Google Maps
A mother and her two young children are being treated in hospital after a man threw a corrosive substance at them in south London.
A total of nine people were injured, including three officers and two others who tried to help.
The Metropolitan Police said emergency services were called to Lessar Avenue, near Clapham Common, at 7.25pm GMT.
Police are searching for the suspect and are using a helicopter in their operation.
Photos from the scene show an abandoned silver hatchback abandoned with its doors open on the Lessar Avenue.
Det Supt Alexander Castle said: "While tests are ongoing to determine what the substance is, at this stage we believe it to be a corrosive substance."
She described the attack as "horrific".
London assembly member Marina Ahmad said on social media there had been a traffic collision on Lessar Avenue "with a man assaulting occupants in a car".
Three police officers who responded to the incident suffered what are believed to be minor injuries, the Met said.
The London Ambulance Service said five of the nine injured were taken to a major trauma centre.
"Three patients were taken to a local hospital and the other was discharged at the scene," as spokesman told the BBC.
The Met said no arrest has been made. Police said they would provide an update on the conditions of the injured people as soon as they can.
London Fire Brigade confirmed two crews from Clapham and Battersea fire stations attended the scene to help provide emergency care to the mother and two children.
"Crews also used specialist equipment to detect a corrosive substance that is believed to have been used in the incident.
"The Brigade was called at 19:35 and the incident was over for firefighters by 21:21."
- This story was first published by the BBC