Firefighters rescued a woman and two children from a fire at a fast food takeaway shop with a flat above on High Road in Tottenham.
Half of the ground floor shop, part of the first floor flat and all of the ducting (the ventilation system) which ran from the ground floor to the second floor of the flat above were destroyed by fire.
One woman and two children were rescued by crews via a first floor flat roof. They were all taken to hospital by London Ambulance Service crews.
The Brigade's Fire Investigators believe the fire was accidental and caused by grease in the ventilation system igniting in a fast food shop on the ground floor and setting fire to timber floorboards.
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.
"This is also a timely reminder to make sure to test your smoke alarms. The residents were asleep at the time of the fire and were awoken by smoke alarms sounding inside the property. Upon investigation, they discovered thick smoke on the first floor.
"This incident shows just how important it is to have smoke alarms in every room where a fire can start in your home, plus a heat alarm in the kitchen and bathroom."
The Brigade was called at 0058 and the fire was under control by 0302. Ten fire engines and around 70 firefighters from Tottenham, Edmonton, Stoke Newington, Walthamstow, Enfield and Hornsey fire stations were at the scene.