Four fire engines and 21 firefighters and officers were called to a storage unit alight in Islington this morning.
The single story building in Stroud Green Road was partially damaged by fire and two cars were completely damaged in the blaze.
Two other cars were also half damaged by fire.
Watch manager Graham Foskett, who was at the scene, said: "A car was alight in an alleyway when crews arrived and it then spread to a further three cars.
"They all looked like they had been dumped and flames then spread to the outside of an outbuilding."
The Brigade was called at 0149 and the fire was under control by 0308. Crews from Hornsey and Stoke Newington attended the scene.