Three boys were stabbed in Northolt Road near South Harrow station around 4pm yesterday (March 5).
The victims – two 16-year-old boys and one 15-year-old boy – were treated at the scene by the ambulance service before being taken to hospital.
The two older boys have been discharged, but the 15-year-old remains in a life threatening condition.
Police were called to an argument outside a property on the road and a boy was arrested on suspicion of grievous bodily harm.
The suspect remains in custody while a crime scene remains in place and enquiries are ongoing.
A Metropolitan Police spokesperson said: “Officers were called to a reported altercation outside an address in Northolt Road, Harrow at 16:00hrs on Wednesday, 5 March.
“Two 16-year-old boys and one 15-year-old boy were stabbed in the incident.
“The three victims received treatment at the scene from the London Ambulance Service and were transferred to hospital.
“The 15-year-old boy remains there in a life-threatening condition. The other boys have been discharged.
“A 16-year-old boy was arrested overnight on suspicion of grievous bodily harm and taken into police custody.
“Enquires are ongoing and a scene remains in place.”
