Emergency services were called to Harrow Road, near the junction of Chippenham Road, yesterday (July 10) at 7.07pm.
The London Ambulance Service said this is due to an injured person.
He was treated at the scene before he was taken to hospital as a priority.
It is understood the incident involved a knife, however this has not been confirmed.
But the Metropolitan Police has been approached for further information.
A London Ambulance Service spokesperson said: “We were called at 7.07pm yesterday (10 July) to reports of an injured person in Harrow Road, W9.
“We sent an ambulance crew and two paramedics in fast response cars to the scene.
“We treated a patient at the scene and took him to a major trauma centre as a priority.”
