Four fire engines and around 25 firefighters were called to a fire at a shop with flats above on Artillery Lane in The City.
A small part of the basement was damaged by the fire. There were no reports of any injuries.
The Brigade was called at 0616 and the fire was under control by 0806. Fire crews from Whitechapel, Shoreditch, Dowgate and Shadwell fire stations attended the scene.
The Brigade’s fire investigators believe the fire was accidental and the cause was either a fault in an electric vacuum heater or the heater being accidentally switched on and setting light to nearby items.