Four fire engines and 21 firefighters and officers were called to a fire at block of flats in Camberwell Station Road in Camberwell.
Part of a four-roomed flat on the third floor was damaged by the fire. One man and two children left the flat before the Brigade arrived. They were taken to hospital suffering smoke inhalation by London Ambulance Service crews. A further 25 people left the building before the Brigade arrived.
The Brigade was called at 0406 and the fire was under control at 0513. Fire crews from Brixton, Lambeth and Old Kent Road fire stations attended.
The cause of the fire is under investigation.