Schoolgirl with potentially life changing injuries after west London 'acid' attack
A 14 year old, 16 year old, 27 year old and two police officers were taken to hospital.
Police on patrol were flagged down at 16:42hrs on Monday, 30 September by staff at a school in Alfred Road W2 after a substance was allegedly thrown at pupils and a staff member.
Officers responded with paramedics and the London Fire Brigade and found three people injured.
A 14-year-old girl, whose injuries may potentially be life-changing was taken to hospital, where she remains.
A 16-year-old boy, whose injuries are not life-threatening or life-changing also remains in hospital.
A 27-year-old woman - whose condition is not life-threatening or life-changing was taken to hospital but has since been discharged.
A Metropolitan Police spokesperson said: "Tests of the substance are ongoing. At this stage officers believe it to be acidic.
Urgent enquiries are under way to identify and arrest those responsible.
A number of crime scenes are in place."
Two officers were taken to hospital as a precaution after they reported feeling unwell.
It's understood to have happened outside Westminster Academy school, a message on the school's website confirms the building was closed on Tuesday morning.
Anyone who witnessed the incident, or who has information that could help police, should call 101 quoting CAD 4987/30Sep.
To remain 100% anonymous contact the independent charity Crimestoppers on 0800 555 111.