Eight fire engines and 58 firefighters and officers were called to a fire at a terraced house in Lodge Avenue, Dagenham.
The ground floor, first floor and roof were completely destroyed by the fire. Half of the roof of the adjoining property was also damaged by the blaze.
A woman left the property before the Brigade arrived and was treated for smoke inhalation and taken to hospital by London Ambulance Service crews.
A further eight people were led to safety from the adjoining properties.
The Brigade was called at 1401 and the fire was under control by 1529. Fire crews from Ilford, Dagenham, Barking and Stratford fire stations were at the scene.
The cause of the fire is believed to be a faulty extension lead.