Ten fire engines and around 72 firefighters dealt with a fire in a row of terrace houses on Roffe Gardens in Dagenham.
The whole of the second floor and roof of a mid terraced house was damaged by the blaze. The fire also affected the two neighbouring properties.
One male, one female and three children left the property before the Brigade arrived. The adult male was suffering from smoke inhalation and taken to hospital by London Ambulance Service crews.
The Brigade was called at 2005 and the fire was under control by 2219. Fire crews from Dagenham and surrounding fire stations were at the scene. The cause of the fire is under investigation.