Firefighters are urging smokers to dispose of cigarettes safely after a house fire on Beaumont Road in Harrow.
Half of the first floor of a converted semi-detached house was damaged by fire. Six people left the building before the Brigade arrived. There were no reports of any injuries.
The fire is believed to have involved 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."
The Brigade was called at 1751 and the fire was under control by 1855. Two fire engines from Harrow and Northolt fire stations attended the scene.