Four fire engines and around 25 firefighters were called to a fire at a shop on the High Street in Plaistow.
Part of the store room at the rear of the property was damaged by fire. There were no reports of any injuries.
The alarm was raised by a passer-by who saw smoke coming from the rear of the shop and called the Brigade.
The Brigade was called at 0259 and the fire was under control by 0437. Fire crews from Plaistow, Stratford, East Ham and Poplar fire stations attended the scene.
The Brigade’s Fire Investigators believe the fire was accidental and involved a free standing freezer.