Four fire engines and around 25 firefighters were called to a fire on an industrial estate on Hailey Road in Erith.
A large quantity of rubbish in an outside compound was damaged by fire.
Two propane gas cylinders were involved in the blaze. They were cooled down and removed as some cylinders can explode when exposed to heat. The fire also damaged an external electrical substation.
The Brigade was called at 1448 and the fire was under control by 1730. Fire crews from Erith, Bexley, Plumstead and East Greenwich fire stations were at the scene.
The cause of the fire is believed to be the unsafe disposal of smoking materials, such as a match or cigarette.