Firefighters were called to a fire at an industrial unit on The Sidings in Leytonstone.
A fire involving a 20-litre metal fuel can was out before crews arrived. Two men were taken to hospital by London Ambulance Service crews.
The fire is believed to have been caused by excessive pressure in a fuel can being released near to a heat gun.
A London Fire Brigade spokesperson said: “A fuel can had been positioned inside a van against a panel that was having a vinyl wrap removed using a heat gun, which caused it to expand. When the pressure was released, the heat from the air gun started a fire.
“It’s important to make sure that areas where fuel sources are stored are well ventilated and away from naked flames, heat sources and electrical equipment.”
The Brigade was called at 1843 and the incident was over for firefighters by 1923. Two fire engines from Leyton and Leytonstone fire stations attended the scene.