Four fire engines and around 25 firefighters tackled a fire at a nursery school on Meadow Road in Oval.
Most of a nursery school was damaged by fire. There were no reports of any injuries.
The fire is believed to have been accidental and caused by an electrical event in an extension lead.
A London Fire Brigade spokesperson said: “Some electrical appliances use more power than others, so be mindful not to overload extension leads and always check that you’re using the right fuse for the plug.
“Power-hungry appliances such as kettles, toasters and microwaves, shouldn’t be on the same extension. It’s also important to fully unwind drum extension leads. If you leave them coiled, they can overheat and cause a fire.”
The Brigade’s Control Officers took the first call at 0610 and mobilised crews from Lambeth, Clapham and Brixton fire stations to the scene. The fire was under control by 0813.