Four fire engines and 21 firefighters and officers were called to a fire at a house converted into flats in Sydner Road, Hackney.
Half of a lower ground flat was damaged by fire. Two men and two women left the property before the arrival of the Brigade.
The Brigade was called at 0245 and the fire was under control at 0347. Fire crews from Stoke Newington, Islington, Shoreditch, and Kentish Town fire stations attended the scene.
The cause of the fire is under investigation.