Four fire engines and around 25 firefighters were called to a fire at a house on Garth Close in Morden.
Part of the roof of an end of terraced house was damaged by fire. Four people left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 2117 and the fire was under control by 2224. Fire crews from Sutton, Mitcham, Tooting and Wallington fire stations attended the scene.
The Brigade's Fire Investigators believe the fire was caused by a downlight which came into contact with combustible materials.