Six fire engines and around 40 firefighters were called to a fire on Constable Close in Barnet.
Firefighters tackled a fire at a four-storey block of flats, where part of a flat on the third floor was destroyed. Around 12 people left the building before the Brigade arrived, there were no reports of any injuries.
The Brigade was called at 1502 and the fire was under control by 1728. Fire crews from Southgate, Hornsey, Barnet and other surrounding fire stations attended the scene.
The cause of the fire will be investigated.