Eight fire engines and around 60 firefighters were called to a fire at a disused block of flats in Ripple Road in Barking.
Part of the second floor and part of the roof of a disused three-storey block of flats was damaged by fire.
The Brigade was called at 0408 and the fire was under control at 0643. Fire crews from Barking, East Ham, Plaistow, Dagenham, Stratford and Poplar fire stations attended the scene.
The cause of the fire is under investigation.