Eight fire engines and around 60 firefighters were called to a fire at a suspected cannabis factory at an industrial estate on Marsh Way in Rainham.
The whole of the first floor of a two storey industrial unit was destroyed by fire. A small part of the roof was also damaged by the blaze.
Station Commander Alan Bendell was at the scene, he said: "There's a lot of heavy smoke in the local area so residents living nearby were advised to shut doors and windows this morning."
The Brigade was called 0821 and the fire was under control by 1035. Fire crews from Wennington, Dagenham, Barking, East Ham and surrounding fire stations were at the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.