Eight fire engines and around 60 firefighters tackled a fire at a flat building on Benworth Street in Mile End.
The whole of the third floor and a small part of the fourth floor were damaged by the fire. Three people left before the arrival of the Brigade and were treated on scene by London Ambulance Service crews.
The Brigade's Control Officers received over 40 calls regarding the fire.
The Brigade was called at 1515 and the fire was under control by 1619. Firefighters from Plaistow, Dockhead, East Greenwich and surrounding fire stations attended the scene.
The cause of the fire is under investigation.