Ten fire engines and around 70 firefighters responded to a fire on Institute Place, Hackney.
The fire was located in a first floor flat, in a residential block of five floors. Traffic in the surrounding area will be impacted as crews remain on scene. There are no reports of any injuries.
The Brigade was first called about the incident at 1959, and Control Officers mobilised crews from Stoke Newington, Bethnal Green, Homerton and surrounding fire stations to the scene. Firefighters had the incident under control by 2055.
The cause of the fire is believed to have been accidental, caused by the unsafe disposal of smoking materials.