Four fire engines and around 25 firefighters tackled a fire on Brecknock Road in Tufnell Park.
Part of a third-floor flat and fourth-floor balcony was damaged by fire. One man left the flat before firefighters arrived. He was taken to hospital by London Ambulance Service crews suffering from smoke inhalation. Around 30 other people left the building before firefighters arrived.
A London Fire Brigade spokesperson said: “Firefighters recommend that you have a look at our online Home Fire Safety Checker to make sure there are no hidden hazards in your home.
“The online tool will ask you a series of questions that will help us work out the level of risk in your home, or the home of someone you care for. It only takes a few minutes to get tailored advice to keep yourself and loved ones safe from fire.”
The Brigade's 999 Control Officers received more than 10 calls about the fire.
The Brigade was called at 2315 and the fire was under control by 0024. Crews from Kentish Town, Holloway, Islington and Euston fire stations attended the scene.
The cause of the fire is under investigation.