Four fire engines and around 25 firefighters were called to a house fire on Thornton Road in Balham.
Part of the ground floor of a terraced house was damaged by fire. There were no reports of any injuries.
Sub Officer Glen Corbett, who was at the scene, said: "On arrival we could see smoke coming out of the window of the house.
"The residents were out at the time of the fire and crews worked quickly to search the building and bring the fire under control."
The Brigade was called at 1110 and the fire was under control by 1130. Fire crews from Clapham, Tooting and Brixton fire stations attended the scene.
The cause of the fire is under investigation.