Four fire engines and around 25 firefighters tackled a house fire on Third Avenue in Manor Park.
Half of the first floor of a terraced house was damaged by fire. Three adults and two children left the building before the Brigade arrived. They were assessed on scene by London Ambulance Service crews and a child, a man and a woman were taken to hospital.
The fire is believed to have been accidental and involved an extension lead.
A London Fire Brigade spokesperson said: “Some electrical appliances use more power than others, so be mindful not to overload extension leads and always check that you’re using the right fuse for the plug.”
The Brigade was called at 1734 and the fire was under control by 1913. Fire crews from Stratford, Ilford and East Ham fire stations attended the scene.