Fifteen fire engines and around 100 firefighters tackled a fire at a takeaway restaurant with flats above on Seven Sisters Road in Holloway.
The ground-floor restaurant was destroyed and a flat roof on the ground floor collapsed. Part of two flats on the first and second floors of the building were also damaged by fire. Five people were taken to hospital by London Ambulance Service crews after suffering from smoke inhalation.
Station Commander Mike Watts, who was at the scene, said: "There are road closures in place and we urge people to avoid the area, particularly as we head into rush hour, due to congestion.
"The fire produced a lot of smoke in the vicinity and local residents were advised to keep their windows and doors closed while crews brought the fire under control."
The Brigade's Control Officers took the first of 19 calls to the fire at 0345 and mobilised fire crews from Holloway, Kentish Town, Islington, Euston and surrounding fire stations to the scene. The fire was under control by 0755.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.