Six fire engines and 35 firefighters and officers were called to a fire at a flat in a high rise block of flats in Station Road, Edgware.
Part of a flat on the fifth floor of the thirteen-storey building was damaged by fire.
About 50 people were evacuated from the building while firefighters were at the scene. There were no reports of any injuries.
The Brigade was called at 1030 and the fire was under control at 1150. Fire crews from Stanmore, Mill Hill, Hendon and Harrow fire stations attended the scene.
The cause of the fire is believed to be accidental.