LONDON (AP) — Two teens were hospitalized with injuries after a male suspect on a scooter threw what was believed to be acid on them outside a London school, police said Tuesday.

A 14-year-old girl may have “life-changing” injuries from the attack that occurred Monday afternoon outside Westminster Academy, the Metropolitan Police said.

A 16-year-old boy was not as seriously injured, but remained in the hospital.

A teacher who rushed to help them also was hospitalized after being exposed to the substance but was released after treatment.

“A member of staff bravely and selflessly rushed to provide first aid to the two victims, sustaining injuries herself in the process,” police said in a statement.

Two police officers who felt ill after responding to the attack were taken to the hospital as a precaution but later released.

The school was closed Tuesday and classes were held online.

The suspect, who was wearing a mask or other face covering, fled the scene. Police appealed to the public for more information about him or the attack.