The incident happened in Joel Street, Northwood Hills just after 1pm yesterday (July 7).
Officers and London Ambulance Service crews attended and found three teens who had been stabbed.
They were treated at the scene before being taken to hospital.
One victim, 19, has been discharged from hospital – his injuries were not deemed life-changing or life-threatening.
He was arrested on suspicion of affray and remains in police custody.
The other two victims remain in hospital.
The injuries of one, aged 18, have not been deemed life-changing or life-threatening.
The condition of the 17-year-old victim is currently unknown.
They have also been arrested on suspicion of affray
A spokesperson for the Metropolitan Police said: “At 13:04hrs on Monday, 7 July officers and the London Ambulance Service responded to reports of a stabbing on Joel Street, Northwood Hills.
“Three men were found at the scene with stab wounds. They were treated by paramedics and then taken to hospital.
“One victim aged 19 has been discharged from hospital – his injuries were not deemed life-changing or life-threatening. He was arrested on suspicion of affray and remains in police custody.
“The other two victims remain in hospital. The injuries of one, aged 18, have not been deemed life-changing or life-threatening – we await an update on the condition of the second man, aged 17.
“They have also been arrested on suspicion of affray.
“Several lines of enquiry are ongoing.”
Anyone with information about the incident is urged to call police on 101 quoting CAD 3766/07JUL or to contact Crimestoppers anonymously on 0800 555 111.
