Four fire engines and 21 firefighters and officers were called to a flat fire in Robinswood Gardens in Walthamstow.
Half of a flat on the first floor was damaged by fire.
The Brigade was called at 1206 and the fire was under control at 1255. Fire crews from Walthamstow, Chingford and Tottenham fire stations are at the scene.
The cause of the fire is under investigation.