Eight fire engines and 58 firefighters and officers were called to a fire at a maisonette above some shops on Pickford Lane in Bexleyheath.
Most of the maisonette on the first and second floor was destroyed by fire. The fire also damaged the roof of the maisonette and its neighbouring properties.
Two adults and a child left the property before the Brigade arrived and were treated at the scene for smoke inhalation by London Ambulance Service. 16 other people evacuated from neighbouring properties before the Brigade arrived.
The Brigade was called at 2326 and was under control by 0234. Fire crews from Bexley, Erith, Plumstead, Sidcup, East Greenwich, Eltham and Orpington fire stations were at the scene.
The cause of the fire is under investigation.