Four fire engines and around 25 firefighters were called to a fire at a takeaway restaurant on Seven Sisters Road in Holloway.
Part of the ground floor restaurant was damaged by fire.
Firefighters wearing breathing apparatus led three people to safety from flats above the restaurant. A number of people left the restaurant before the Brigade arrived. There were no reports of any injuries.
Road closures were in place on Seven Sisters Road and Holloway Road.
The fire is believed to have been accidental and caused by unattended cooking oil.
A London Fire Brigade spokesperson said: "Cooking should never be left unattended on the hob or grill - if you have to leave the kitchen, turn off the heat.
"Chip pans and cooking with hot oil can be really dangerous and the risk increases when you start frying food more than once.
“All it can take is for you to become distracted for a few seconds and your cooking oil can quickly go up in flames.”
The Brigade was called at 1123 and the fire was under control by 1228. Firefighters from Holloway, Islington, and Kentish Town fire stations were at the scene.