Six fire engines and around 40 firefighters were called to a flat fire on Chilton Road in Richmond.
Half of the roof of an end-of-terrace house converted into flats was damaged by fire. Three people left the building before the Brigade arrived and were assessed on scene by London Ambulance Service crews.
The Brigade was called at 2108 and the fire was under control by 2223. Fire crews from Richmond, Heston, Acton and Kingston fire stations attended the scene.
The Brigade’s Fire Investigators believe the fire was accidental and involved a lighting transformer, used to transform voltage down to levels that are suitable for household lighting.