Six fire engines and around 40 firefighters have been called to a fire at a house on Livingstone Road in Thornton Heath.
Half of the ground floor and part of the first floor of a semi-detached house were damaged by blaze.
An older woman left the property, unhurt, before the Brigade arrived.
The Brigade was called at 1205 and the fire was under control by 1351. Fire crews from West Norwood, Clapham, Beckenham and Forest Hill fire stations are at the scene.
The cause of the fire is under investigation.