Two fire engines and around 10 firefighters were called to reports of an explosion at a flat on Toland Square in Putney.
Most of a three roomed flat on the ground floor of a three-storey block of flats was damaged by the explosion. Two women left the building before the Brigade arrived. They were treated on scene by London Ambulance Service crews and one of the women was taken to hospital.
Residents from surrounding properties were evacuated as a precaution.
The Brigade was called at 1411 and the incident was over for firefighters by 1515. Fire crews from Wandsworth and Richmond fire stations attended the scene.
The explosion is believed to have involved a gas supply.