Ten fire engines and around 70 firefighters were called to a fire at a school on Leigham Court Road in Streatham.
Part of the roof of a school building was damaged by fire. There have been no reports of any injuries.
People in the local area were advised to keep their windows closed due to potential smoke travel.
Leigham Court Road was closed between the junctions of Chestnut Close and Leaf Grove.
The Brigade received the first of six calls at 0008 and Control Officers mobilised crews from West Norwood, Norbury, Tooting, Brixton and surrounding fire stations to the scene. A 32-metre turntable ladder from Clapham Fire Station also attended. The fire was brought under control by 0240 but crews have remained on scene throughout the night damping down.
The cause of the fire is under investigation.