Four fire engines and around 25 firefighters were called to a house fire on Grinling Place in Deptford.
Part of the first floor of a two storey terraced house was destroyed by fire. Four people left before the Brigade arrived on scene. Two women, one man and a boy were all suffering from smoke inhalation and were treated on scene by London Ambulance Service.
The Brigade's 999 Control officers were called at 1126 and deployed crews from East Greenwich, Dockhead and Lee Green fire stations. The fire was under control by 1235.
The cause of the fire is under investigation.