SIOUX CITY, Iowa (KCAU) — A vehicle fire in Sioux City has authorities scratching their heads.

Sioux City Fire Rescue responded to the incident Sunday afternoon.

Fire crews arrived at the 2500 block of South St. Aubin Street and saw a large amount of smoke in a nearby alleyway. A fan was discovered to be on fire and fire officials worked to quickly extinguish the flames.

Authorities are unsure whether the fire had started inside or outside the van.

Assistant fire chief Robert Wilson said it’s possible the vehicle caught on fire by itself.

“It would be somewhat unusual, but it’s not unheard of. We have had vehicles that were operating previously and maybe it’s been a few hours and sometimes a slow ignition process, they can ignite a few hours later just because of what was initially burning,” said Wilson.

No surrounding property outside of the vehicle was damaged.

No other information is available at this time and we will update once we learn more.