Eight fire engines and around 60 firefighters tackled a fire at a restaurant and nightclub on Croydon High Street.
Part of an external store room connected to the main building at the rear was damaged by fire. There were no reports of any injuries.
Firefighters removed and cooled five gas cylinders to an ambient temperature as a precaution as some cylinders can explode when exposed to heat.
Station Commander Steve Howlett, who was at the scene, said: "Croydon High Street was closed to traffic whilst we worked to make the scene safe and we urged people to avoid the area where possible."
The Brigade was called at 2032 and the fire was under control by 2143. Fire crews from Croydon, Wallington, Norbury and surrounding fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.