Eight fire engines and around 60 firefighters tackled a fire in a block of flats in Plaistow Road, Plaistow.
Part of a flat on the 13th floor was damaged by the fire. Four men suffering from smoke inhalation and one man suffering with burns were treated at the scene by London Ambulance Service crews and taken to hospital.
The Brigade was called at 1259 and the fire was under control by 1446.
Fire crews from Plaistow, Stratford, Poplar, Leytonstone and surrounding stations were at the scene.
The cause is believed to have been the unsafe disposal of cigarettes.
• Make sure you have smoke alarms fitted in every room you regularly use in your home including in the hallways.
• Never smoke in bed.
• Always ensure you stub out cigarettes properly and dispose of them carefully.
• Keep matches and lighters out of children's reach.
• Never leave lit cigarettes or cigars unattended.
• Empty ashtrays carefully, ensuring all smoking materials are stubbed out and cold.
• If you must smoke, do it outdoors.