Six fire engines and around 40 firefighters were called to a house fire on Wilde Place in Tooting.
The roof of a semi-detached house was damaged by fire, along with a small part of the adjoining property's roof. There were no reports of any injuries.
The Brigade was called at 0407 and Control Officers mobilised crews from Tooting, Battersea, Wandsworth, Fulham and Norbury fire stations to the scene, along with a 32-metre turntable ladder from Clapham. The fire was brought under control by 0540.
The fire is believed to have been caused by a lightning strike.