Four fire engines and around 25 firefighters were called to a flat fire on Barker Drive in Camden.
Part of a four-roomed flat on the first floor of the building was damaged by fire. The first, second and third floors of the building were affected by smoke logging. There were no reports of any injuries.
The fire was discovered by a member of the public who was passing by and saw smoke coming from the roof. They then called the Brigade.
A London Fire Brigade spokesperson said: “There were no smoke alarms in this property. Homes need multiple smoke alarms or you won’t be properly covered.
"Ideal spots for smoke alarms include rooms where you leave electrical equipment running like satellite boxes, computers or heaters; any room where you smoke, and anywhere you charge your mobile or laptop.
“As a minimum you should have smoke alarms on every floor - in the hallways and the rooms you use the most, plus a heat alarm in the kitchen. They should be tested regularly."
The Brigade was called at 0650 and the fire was under control by 0731. Fire crews from Kentish Town, Holloway and Euston fire stations attended the scene.
The fire is believed to have been accidental and caused by water coming into contact with electrical wiring.