Four fire engines and around 25 firefighters were called to a fire at a house in Thorneloe Gardens, Croydon.
The first floor of a semi-detached house was destroyed by the blaze. One woman was treated at the scene by London Ambulance Service crews.
The Brigade was called at 1456 and the fire was under control at 1539. Fire crews from Croydon, Wallington and Purley fire stations attended the scene.
The cause of the fire is under investigation.