A 14-year-old girl has been seriously injured after a substance, believed to be acidic, was thrown at her and two others outside a school in west London.
Metropolitan Police officers were flagged down by a member of staff at Westminster Academy after the incident in Alfred Road, Westbourne Park, at about 16:40 BST on Monday.
The girl remains in hospital with potentially life-changing injuries.
A boy aged 16 remains in hospital with non life-changing injuries, and a woman aged 27 has been sent home from hospital after also being hurt in the attack.
Two police officers were taken to hospital as a precaution after they reported feeling unwell.
A Met police spokesperson said: “Tests of the substance are ongoing. At this stage officers believe it to be acidic.
“Urgent inquiries are under way to identify and arrest those responsible.”
Westminster Academy is closed following the incident, with lessons taking place online and many staff working from home.
A number of crime scenes remain in place as investigations are carried out.
