Twenty five fire engines and around 150 firefighters were called to a fire at a car repair workshop at Chadwell Heath Industrial Estate on Kemp Road in Dagenham.
Half of a single storey workshop was alight.
Station Commander James Ryan is at the scene, he said: "The incident is now under control but crews will remain on scene for several hours to ensure there are no remaining pockets of fire. The advice for local residents remains - keep windows and doors shut due to heavy smoke.
"The whole of Kemp Road is currently closed and motorists are advised to avoid the area for the foreseeable future as the fire crews bring this protracted incident to its conclusion."
At the height of the incident the Brigade’s 999 Control centre received 75 calls alerting them to the blaze.
The Brigade was called at 0827 and the incident was under control by 1354. Fire crews from Dagenham, Ilford, Romford, Hornchurch, Hainault, East Ham, Barking, Walthamstow, Harold Hill, Stratford, Plaistow, Wennington, Leytonstone and other surrounding fire stations attended the incident.
The cause of the fire is unknown at this stage, pending further investigation by the Metropolitan Police.