Four fire engines and around 25 firefighters tackled a fire at a railway arch on Carlisle Lane in Lambeth.
Part of the archway was damaged and two electric mopeds were destroyed by the fire. There are no reports of any injuries.
The fire is believed to have been accidental and was caused by the failure of a lithium-ion battery.
The Brigade was called at 0640 and Control Officers mobilised crews from Lambeth, Dowgate and Old Kent Road fire stations to the scene. The fire was extinguished by 0745.