Four fire engines and around 25 firefighters were called to a flat fire on Warwick Road in Sutton.
A first floor flat was destroyed and part of the loft of a semi-detached house converted into flats was damaged by fire. Three people were taken to hospital by London Ambulance Service crews.
One of the Brigade's 32-metre turntable ladders was used at the scene as a water tower to tackle flames from height.
The Brigade’s Control Officers took the first of 17 calls to the fire at 1023. Fire crews from Mitcham, Sutton, Croydon and Clapham fire stations are at the scene. The fire was under control by 1227.
The cause of the fire is under investigation.