Four fire engines and 21 firefighters and officers were called to a fire at a block of flats in Ross Road, Wallington last night.
Part of a flat on the second floor of the four-storey building was damaged by fire.
Two people left the affected flat and another 20 people left the building before the arrival of the Brigade. There were no reports of any injuries.
The fire is believed to have been caused by an electrical fault within a consumer unit.
The Brigade was called at 2120 and the fire was under control at 2229. Fire crews from Wallington, Croydon and Purley fire stations attended the scene.