Four fire engines and around 25 firefighters were called to a house fire on Finch Gardens in Chingford.
Part of the first floor of a semi-detached house was damaged by fire. Four people left the building before the Brigade arrived. One woman was taken to hospital by London Ambulance Service crews.
The Brigade was called at 0237 and the fire was under control by 0349. Fire crews from Chingford, Walthamstow, Woodford and Edmonton fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.