Four fire engines and around 25 firefighters tackled a fire at a block of maisonettes on Bermondsey Street in Southwark.
Most of a second and third floor maisonette was damaged by the fire. Three people were treated on scene by London Ambulance Service.
Control Officers took the first of three calls at 0606 and mobilised crews from Dockhead, Old Kent Road, Dowgate and Whitechapel fire stations to the scene. The incident was over for firefighters at 0811.
The fire is believed to have been accidental and was caused by an electrical fault.