Four fire engines and around 25 firefighters tackled a fire at a house converted into flats on Kennington Oval in Vauxhall.
Part of the decking on the flat roof of a mid-terraced building was damaged by fire. Part of a wooden fence was also damaged by the blaze. Two gas cylinders were removed from the fire and cooled to an ambient temperature as a precaution, as some gas cylinders can explode when exposed to heat. There were no reports of any injuries.
The fire is believed to have been accidental and caused by the unsafe disposal of smoking materials.
A London Fire Brigade spokesperson said: "We’d rather you didn’t smoke at all, but if you are a smoker, it’s absolutely vital you ensure your cigarette is completely out when you’ve finished smoking it.
“If you don’t, you risk causing a fire which could not only destroy your home, but also cost you your life.
“Never leave lit cigarettes unattended and make sure to stub them out properly and dispose of them carefully when you have finished smoking.”
The Brigade was called at 1818 and the fire was under control by 2001. Fire crews from Lambeth, Brixton and Peckham fire stations attended the scene.