Police were called to Neasden Lane at 10pm yesterday (February 22) to reports of the altercation.
At the scene, a man was found with stab wounds to his hand.
He was treated at the scene by medics before he was taken to hospital.
The Metropolitan Police says that there have been no arrests at this time, but investigations are ongoing.
Locals said there were several police cars and ambulances along Neasden Lane between the BP petrol station and Neasden station at the time.
A Met Police spokesperson said: “Police were called to a report of an altercation outside of a garage on Neasden Lane, Neasden at 22:02hrs on Tuesday, 25 February.
“A man suffered a stab wound to his hand and was taken to hospital.
“No arrests were made and enquiries are ongoing.”
Witnesses or anyone with any information or footage is asked to call police 101 or message @MetCC on X quoting CAD 7821/25FEB.
