Four fire engines and around 25 firefighters were called to a fire at a hotel on Kilburn High Road in Camden.
Part of a two-roomed apartment on the third floor was damaged by the fire. Around 50 people left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 0754 and the fire was under control by 0845. Fire crews from West Hampstead, Paddington and Willesden fire stations attended the scene.
The Brigade's fire investigators believe the cause of the fire was due to a loose connection within an immersion heater.