Six fire engines and around 30 firefighters responded to a fire on Crescent Wood Road, Dulwich Wood.
The fire occurred in a residential block of seven floors. A ground floor electrical intake was destroyed by the fire. Around 100 people left the property before crews arrived, and there are no reports of any injuries.
The Brigade was first called about the incident at 2351, and crews had the incident under control by 0053. Firefighters from Forrest Hill, West Norwood, Beckenham and surrounding fire stations attended the scene.
The fire is believed to have been accidental, caused by a failure in the electrical intake.