Four fire engines and around 25 firefighters tackled a fire at a three storey terraced house on Shelgate Road in Clapham.
Half of the first floor of a six-roomed flat was damaged by the fire. One person was rescued from the first floor by firefighters wearing breathing apparatus using a short extension ladder and was taken to hospital by London Ambulance Service crews.
The Brigade was called at 1741 and the incident was over for firefighters at 1843.
The cause of the fire is under investigation.