Firefighters were called to a fire at a sheltered housing accommodation block on Watersplash Close in Kingston.
A small part of a first floor flat was damaged by fire. A woman was taken to hospital by London Ambulance Service crews. Two further people left the building before the Brigade arrived.
A London Fire Brigade spokesperson said: “The alarm was raised by a resident who was asleep inside their flat and was awoken by a loud bang. Upon investigating, they opened their store cupboard and found the consumer unit alight. They then promptly left the building and waited for the Brigade to arrive.
“Crews worked quickly to bring the fire under control and ventilated the property of smoke.”
The Brigade was called at 0207 and the fire was under control by 0239. Two fire engines and around 10 firefighters from Surbiton and Kingston fire stations attended the scene.
The Brigade’s Fire Investigators believe the fire was caused by an electrical fault within the consumer unit.