Six fire engines and around 40 firefighters tackled a fire at a house on London Road in Thornton Heath.
The fire affected half of the ground floor and part of the first floor of a semi-detached house converted into flats. Part of the roof of a second semi-detached house was also damaged by the fire. One woman was treated on scene by London Ambulance Service.
Control Officers took the first of 11 calls at 2145 and mobilised crews from Norbury, Croydon, Woodside and surrounding fire stations to the scene. The fire was extinguished by 2321.
The cause of the fire is under investigation.