Six fire engines and around 40 firefighters tackled a fire on Waterloo Road in Brent Cross.
Part of an underground car park beneath a three-storey residential building was damaged by the fire. There were no reports of any injuries.
Local residents were advised to keep their windows and doors closed due to large amounts of smoke being produced from the fire. People were advised to avoid the area while the incident was ongoing.
The Brigade's 999 Control Officers took 10 calls regarding the fire.
The Brigade was called at 1505 and the fire was under control by 1617. Firefighters from Hendon, Willesden, West Hampstead and surrounding fire stations attended the scene.
The cause of the fire is under investigation