Ten fire engines and around 70 firefighters were called to a fire at a derelict sports centre on Imperial Way in Croydon.
Most of the two-storey building was alight. There are currently no reports of any injuries.
Two of the Brigade's 32-metre turntable ladders were used at the scene as water towers to tackle flames from height. Drones were also deployed to survey the incident from above, providing live images and thermal imagery. This provided Incident Commanders with a vital aerial view, helping them develop effective tactics and assess the area.
Station Commander Tony Perks, who was at the scene, said: "Crews are expected to be at the scene of the fire throughout the night damping down remaining hot spots.
"The fire was producing smoke in the area and we advised local residents and businesses to keep windows and doors closed."
The Brigade's Control Officers took the first of five calls to the fire at 1626 and sent crews from Croydon, Purley, Wallington, Norbury, Mitcham and surrounding fire stations to the scene. The fire was under control by 2154.
The cause of the fire is under investigation.