Four fire engines and around 25 firefighters were called to a house fire on Riverdale Road in Plumstead.
Half of the ground floor and half of the first floor of the two storey house were destroyed by fire.
One woman and one man left the property before the Brigade arrived. Both were treated on scene by London Ambulance Service who took both people to hospital.
The Brigade was called at 0339 and the incident was over by 0543. Fire crews from Plumstead, Erith and East Greenwich fire stations were in attendance.
The cause of the fire is under investigation by the Brigade's fire investigators and the Metropolitan Police Service.