Eight fire engines and around 60 firefighters were called to a fire at a block of flats on Raven Close in Romford.
The whole of the roof of the block of flats was damaged by fire. There were no reports of any injuries.
Station Manager Dean Wilkinson, who was at the scene, said: "Crews worked hard to bring the fire under control."
The Brigade was called at 1625 and the fire was brought under control by 1901. Fire crews from Hornchurch, Harold Hill, Dagenham, Romford, Ilford, Hainualt and Barking fire stations attended the scene.
The cause of the fire is undetermined.