Six fire engines and 35 firefighters and officers were called to a fire at a block of flats in Palmerston Road in Wood Green.
A water tank room on the roof was destroyed by fire.
Approximately 20 people left the building before the arrival of the Brigade.
Watch Manager Andy Bathie, who was at the scene, said: “This was a challenging fire for crews as there were some cylinders involved in the fire. Our priority was to cool down the cylinders as they can explode when they are exposed to heat.”
The Brigade was called at 1948 and the fire was under control at 2220. Fire crews from Southgate, Hornsey and Tottenham fire stations attended the scene.
The cause of the fire is believed to be accidental.