Eyewitnesses say dozens of armed officers surrounded a property in Larch Road on Tuesday (February 4) after being called at 3.40pm.
A man has been arrested on suspicion of possessing a firearm and has been taken to a police station, where he remains in custody.
People living near Gladstone Park were puzzled to see a police helicopter hovering above the area between Cricklewood and Willesden.
According to one person, around 30 officers were in Larch Road.
A Metropolitan Police spokesperson said: “Police were called at 3.40pm on Tuesday (February 4) to reports of a man believed to be in possession of a firearm at an address on Larch Road, NW2.
“Officers, including firearms officers, attended.
“A man was arrested on suspicion of possession of a firearm. He has been taken to a north London police station where he remains in custody.”
