Four fire engines and around 25 firefighters tackled a pub fire on Kentish Town Road in Kentish Town.
Part of the ducting in the ventilation system from the ground to the third floor was damaged by fire. Around 60 people left the building before the Brigade arrived. There were no reports of any injuries.
The fire is believed to have been accidental and caused by fat and grease inside the ducting igniting.
A London Fire Brigade spokesperson said: “We’d like to remind restaurant and takeaway owners to ensure they don’t have dirty ducting. If you don’t clean the ducting in your extraction system regularly, you’re at a greater risk of ducting fires.
"You should also make sure you keep the hob, cooker hood and extractor fan clean too – built up fat and grease can ignite and cause a fire."
The Brigade’s Control Officers took 10 calls to the fire. The first call was at 1229 and the fire was under control by 1356. Control mobilised fire crews from Kentish Town, Euston, West Hampstead and Hornsey fire stations to the scene.