Six fire engines and 35 firefighters and officers are tackling a fire affecting three terraced houses on Fanshawe Crescent in Dagenham.
Two houses had fire damage to first floor and roof. The fire also spread to an adjacent properties roof.
The fire is believed to have started in the garden. There are no reports of any injuries.
The Brigade was called at 1330 and the fire was under control by 1431. Crews from Dagenham, Ilford, Hornchurch, Romford and East Ham fire stations are attending the scene. The cause of the fire is under investigation.