Six fire engines and around 40 firefighters tackled a flat fire on Buckleigh Road in Streatham that broke out in the early hours of Friday morning.
A person who was rescued by firefighters has sadly died of their injuries.
Half of a ground-floor flat in a converted, two-storey house was damaged by the fire. Firefighters rescued a man from the ground floor. A further five people left the building before the Brigade arrived. Two people were taken to hospital by London Ambulance Service crews.
The Brigade was called at 12.10am and the fire was under control at 1.02 am
Fire crews from Norbury, West Norwood and Tooting fire stations were in attendance.
The cause of the fire is under investigation.
A Spokesman for the Met Police said: Police were called at about 12.15am on Friday, 21 April to reports of a fire at a residential address on Buckleigh Road, SW16.
Emergency services attended. The London Fire Brigade (LFB) rescued a man from inside and he was taken by the London Ambulance Service to a South London hospital.
Despite the efforts of the medical staff, the man died a short time later. His family has been informed.
Officers from the Central South CID are working alongside the LFB to establish the cause of the fire.
Anyone with any information is asked to call the police on 101 or Tweet @MetCC quoting reference CAD 83/21Apr.