Eight fire engines and 58 firefighters and officers dealt with a fire in a flat on Myrtle Road in Harold Hill.
The whole of a flat on the second floor was damaged by the blaze. Part of the roof was also destroyed..
Ten people left the building before the Brigade arrived. A further 20 people from neighbouring properties were also led to safety as a precaution.
The Brigade was called at 1059 and the fire was under control by 1257. London firefighters from Harold Hill, Ilford, Dagenham, Hainault, Hornchurch attended alongside two fire engines from Brentwood fire station in Essex. The cause of the fire is under investigation.