Four fire engines and 21 firefighters and officers were called to a fire at a block of flats in New Kent Road, Elephant and Castle.
Part of a flat on the ground floor was damaged by fire. The occupant of the property was alerted to the fire by a smoke alarm sounding and she left the property before the arrival of the Brigade.
The occupant of the property and a neighbour were treated at the scene for smoke inhalation by the London Ambulance Service. Firefighters wearing breathing apparatus rescued a dog from the flat.
The Brigade was called at 0504 and the fire was under control at 0550. Fire crews from Deptford, Old Kent Road, Dockhead and New Cross fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.