Firefighters rescued three people after a fire broke out on Teesdale Street in Bethnal Green, E2 this morning. Another man was also injured.
A large part of a flat on the first floor of the four-storey building was damaged by fire. Part of a flat on the second floor was also damaged.
The Brigade's fire investigation team believe the fire was accidental and was due to the unsafe disposal of smoking materials.
A London Fire Brigade spokesperson said: "We would rather people didn’t smoke at all but if they do, vaping is a safer option.
"If you do choose to smoke cigarettes, it is 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 0657 and the fire was under control by 0821.
Four fire crews and around 25 firefighters from Bethnal Green, Shoreditch, Whitechapel and Shadwell fire stations attended the incident.