Four fire engines and around 25 firefighters were called to a flat fire on Windsor Street in Islington.
A small part of a four-roomed flat on the second floor of the building was damaged by fire. There were no reports of any injuries.
Leading Firefighter Michael Hailey, who was at the scene, said: “On arrival crews saw light smoke coming out of the second floor window and the residents were already out of the building.
“Smoke alarms were also sounding on arrival. It’s really important that you test your smoke alarms regularly to make sure they are working. You should have smoke alarms in every room where a fire can start, plus a heat alarm in the kitchen and the bathroom.”
The Brigade was called at 1812 and the fire was under control by 1853. Fire crews from Islington, Shoreditch, Euston and Soho fire stations attended the scene.
The cause of the fire has been recorded as undetermined.