Five fire engines and around 35 firefighters were called to a fire in the basement of a block of flats on Waterworks Yard in Croydon.
A mattress was destroyed by fire. Twenty people left the building before the arrival of the Brigade. There were no reported injuries.
The Brigade was called at 0821 and the fire was under control by 0916. Fire crews from Croydon, Woodside and Norbury fire stations attended the scene.
The cause of the fire is under investigation.