Four fire engines and around 25 firefighters were called to a fire at a railway arch on Watt Mews in Streatham.
The railway arch was badly damaged by the blaze. Fortunately there were no reports of any injuries.
The Brigade was called at 1522 and the fire was under control by 1642. Fire crews from Tooting, Norbury and Mitcham fire stations attended the incident.
The cause of the fire is not known at this stage.