Four fire engines and around 25 firefighters were called to a flat fire on Mulgrave Road in Sutton.
A small part of an electrical cupboard on the ground floor of the building was damaged by fire. Around 18 people left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 2008 and the fire was under control by 2029. Fire crews from Sutton, Wallington and Mitcham fire stations attended the scene.
The cause of the fire is believed to have been electrical.