Nine people, including children and police officers, have been taken to hospital after a “corrosive substance” was thrown in south London, police say.
A man was seen fleeing the “horrific incident” at Lessar Avenue, Lambeth.
A woman and her two young children were taken to hospital for treatment. Three others, believed to have come to their aid, also needed medical help.
Three police officers, who responded to the incident, sustained what are believed to be minor injuries.
The Met said that there has been no arrest made, but that they are searching for the assailant using all available resources, including police helicopters.
Detective Superintendent Alexander Castle said: “While tests are ongoing to determine what the substance is, at this stage we believe it to be a corrosive substance.”
London Assembly Member Marina Ahmad said on X (formerly Twitter) that there had been a traffic collision “with a man assaulting occupants in a car”.
Fire engines and ambulances are at the scene of the attack.
Police said they would provide an update on the conditions of the injured people as soon as they can.