Four fire engines and around 25 firefighters were called to a house fire on Ronalds Road in Islington.
Part of the ground floor of a terraced house was damaged by fire. Two women and one man left the building before the Brigade arrived and were treated on scene by London Ambulance Service crews after suffering from smoke inhalation. One woman was taken to hospital.
The fire is believed to have been caused by a chip pan that was left unattended.
Station Officer Wayne Sharp, who was at the scene, said: “On arrival crews were faced with heavy smoke and worked quickly to bring the fire under control and stop it from spreading.
“Fires are more likely to start in the kitchen than any other room in the home.
"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 2351 and the fire was under control by 0049. Fire crews from Holloway, Islington, Stoke Newington and Kentish Town fire stations attended the scene.