An electrical fault is thought to have caused a fire above a garage in Court Drive, Carshalton, last night.
Firefighters from Wallington and Sutton were able to put out the blaze before it spread to the houses attached to the garage after they were called at around 9.45pm.
A fire service spokesman said: "It was a fire in the roof of the garage at the back of the property. There was quite a lot of smoke out in the street.
"Initially we attacked it from outside until we could get in and fight it from the inside. We used a thermal imaging camera at first to check the spread of the fire and then to check for hot timbers after the fire was out.
"The fire could easily have spread to the house if we hadn't been called. We're putting it down to an electrical fault."
No-one was hurt in the blaze and firefighters were on the scene for around two hours.