Six fire engines and around 40 firefighters tackled a fire on West Green Road in South Tottenham.
Part of the flat roof of a communal staircase was damaged by fire. Three people were led to safety via an internal staircase by firefighters wearing breathing apparatus. Around 13 people left the building, which is made up of a shop and flats, and a neighbouring property before firefighters arrived. One woman was treated at the scene by London Ambulance Service crews for smoke inhalation.
Station commander Matthew Hayward, who has been at the scene, said: "There was lots of smoke when crews arrived and two adults and a child were led to safety by firefighters. Crews were also able to deal with the fire in the first floor roof quickly.
"Traffic remains heavy in the area so please avoid if possible."
The Brigade's 999 Control Officers received six calls about the fire.
The Brigade was called at 1151 and the fire was under control by 1249. Crews from Tottenham, Stoke Newington, Walthamstow, Islington and Southgate fire stations attended the scene.
The cause of the fire is under investigation.