Eight fire engines and around 60 firefighters were called to a fire at a disused building on Sydenham Road in Croydon.
Firefighters tackled a fire at a five-storey disused residential block of flats that was under refurbishment. One man left the building before the Brigade arrived and was treated for smoke inhalation at the scene by London Ambulance Service crews.
The Brigade was called at 0421 and the fire was under control by 0533. Fire crews from Croydon, Woodside, Norbury and other surrounding fire stations attended the scene.
The cause of the fire will be investigated.