Four fire engines and 21 firefighters and officers were called to a fire at a house converted into flats in Horsham Road, Bexleyheath.
Part of a flat on the first floor of the building and part of the roof space were damaged by fire.
A man and a woman left the property before the arrival of the Brigade and were treated at the scene for smoke inhalation by London Ambulance Service crews before being taken to hospital..
The Brigade was called at 1820 and the fire was under control at 1941. Fire crews from Bexley, Erith, Eltham and Plumstead fire stations attended the scene.
The cause of the fire is under investigation.