Six fire engines and around 40 firefighters were called to a house fire on Ellison Road in Streatham.
Part of the loft of a semi-detached house was damaged by fire and solar panels fitted to the roof were also damaged by the blaze. There were no reports of any injuries.
Station Commander Jay Tough, who was at the scene, said: "Crews arrived to find a small fire in the loft space of the house, between the boarding and the roof tiles.
"Solar panels were fitted on the roof and crews worked swiftly to make sure the power supply was isolated and to bring the fire under control.
"The residents were all out of the building before the Brigade arrived."
Ellison Road was closed between Kempshott Road and Guildersfield Road whilst crews worked to make the scene safe and we advised people to avoid the area.
The Brigade was called at 0816 and the fire was under control by 0942. Fire crews from Norbury, West Norwood, Tooting and Mitcham fire stations attended the scene.
The fire is believed to have been caused by a squirrel damaging electrical cabling in the loft conversion.