Two fire engines and 10 firefighters were called to fire in a terraced house converted into flats on Grosvenor Avenue in Islington.
Part of the second floor was damaged by fire. The remainder of the second and third floor were damaged by smoke. Twelve people left the property before the Brigade arrived and there were no reports of any injuries.
The Brigade was called at 0541 and the fire was under control by 0635. Firefighters from Islington and Stoke Newington fire stations attended the scene.
A toaster which caught fire and set light to nearby furniture is believed to have caused the fire.