A 14-year-old girl suffered potentially life-changing injuries in a suspected acid attack outside a school.

A boy, 16, and a woman, 27, were also injured when the corrosive substance was thrown at the victims outside Westminster Academy on Monday afternoon.

Police believe the teenagers were approached by a lone suspect on an e-scooter.

A member of school staff was injured after she rushed to help.

Staff flagged down police officers on patrol after the incident in Alfred Road, Westbourne Park, shortly after 4.40pm.

Both teenagers were taken to hospital, with the boy’s injuries described as not life-threatening or life-changing.

The woman has since been discharged.

Scotland Yard said two officers were also taken to hospital as a precaution after they reported feeling unwell.

Detective Chief Inspector Dean Purvis, who is leading the investigation, said: “From our enquiries so far we believe the two young victims were in Alfred Road when they were approached by a lone suspect who threw a substance at them before fleeing down Harrow Road.

“A member of staff bravely and selflessly rushed to provide first aid to the two victims, sustaining injuries to herself in the process. Fortunately she has now left hospital.

“For the 14-year-old girl we might not know for some time how severe her injuries are but at this time they are being treated as life-changing.

“I know how incredibly concerning this incident is to parents and pupils and the wider Westminster community. We are in close contact with the school and local authority, and I can assure people that a thorough investigation is well under way, and that my officers will not stop until the suspect is found and arrested.

“If you have information that can help us, it is imperative that you tell us immediately. The area at the time was busy with people and cars. I am particularly interested in hearing from anyone who might have captured dashcam footage that can help us establish what happened.”

The suspect is described as a tall, slim, black male, wearing dark clothing with his face obscured, possibly by a mask or balaclava. He rode an e-scooter to and from the scene.

Westminster Academy remained closed on Tuesday, with lessons taking place online, according to a statement on its website.

The school’s principal, Numera Anwar, said in a statement: “One pupil, a teacher and a member of the public have been injured in an incident outside the school building on the main road involving an acid-like corrosive substance.

“This was a distressing incident which took place after school hours when students and staff were leaving the school site.

“We are offering support to families and relatives of all involved.

“This is a difficult time for our community and I took the decision to close the school today to allow for a thorough investigation and to ensure the school can resume normally from tomorrow with all safety measures in place.”

Adam Hug, leader of Westminster City Council, said: “This is a truly shocking attack on school pupils and a member of staff.

“The council has been in touch with Westminster Academy and we will provide educational psychologists and any other support to help children through what is a traumatic ordeal. Our thoughts are with all those who have been affected.

“Clearly this attack will be unsettling for the whole academy and the wider community, and we will be working with police to provide reassurance and whatever support we can. We would urge anyone with information about what has happened to contact the police.”

Any witnesses or anyone with information is asked to call police on 101, quoting reference CAD 4987/30 Sept, or call Crimestoppers anonymously on 0800 555 111.

Reporting by PA.