Four fire engines and around 25 firefighters were called to a fire in an outbuilding used as storage for a restaurant on Goodmayes Road in Ilford.
The single-storey outbuilding was destroyed by the fire. There were no reports of any injuries.
Firefighters removed a propane cylinder and cooled it to an ambient temperature as some cylinders can explode when exposed to heat.
The fire was discovered by a member of the public who saw smoke emitting from the doorway and called the Brigade.
The Brigade was called at 1817 and the fire was under control by 1911. Fire crews from Ilford and Dagenham fire stations were at the scene.
The cause of the fire is under investigation.