Six fire engines and 35 firefighters and officers were called to a fire in Essex Road, Islington.
Part of the basement beneath a shop and flats was damaged by fire.
Five people left the premises before the arrival of the Brigade. There were no reports of any injuries.
The Brigade was called at 1249 and the fire was under control at 1423. Fire crews from Holloway, Shoreditch. Euston, Stoke Newington, Kentish Town and Soho fire stations attended the scene.
The cause of the fire is not known at this stage.