Four fire engines and around 25 firefighters were called to a fire at a house converted into flats on Westdown Road in Catford.
Part of the ground floor two roomed flat in the three floored house was destroyed by fire.
One person was rescued by crew via an internal staircase, they were assessed on scene by London Ambulance Service.
The Brigade was called at 0926 and was over by 1034. Fire crews from Forest Hill, Dockhead, Bromley and Peckham fire stations were in attendance.
The cause of the fire has been recorded as undetermined.