Six fire engines and 35 firefighters and officers were called to a roof fire in Udall Gardens in Romford.
Half of the roof across two maisonettes was damaged by fire. Three people left the affected properties before the arrival of the Brigade and were assessed at the scene by London Ambulance Service.
The Brigade was called at 1817 and the fire was under control at 2008. Fire crews from Romford, Hainault, Harold Hill and Ilford fire stations attended the scene.
The cause of the fire is under investigation.