Fire crews battled a large fire on Provincial Road in Windsor Thursday that destroyed a business.

Nearly every firetruck in the city was called to the scene over the noon hour as multiple fires were blazing.

"The smoke started out, and it just got darker and darker as it burned into the building," said witness Bill Kresan as the fire blazed on behind him.

A fire official told CTV News the grass and brush behind J & B Auto Recyclers and Plaza Ontario could have been where the fire started and escalated quickly.

Shop owners at the recycling business say they had hundreds of engines and transmissions inside.

The other two buildings -- Plaza Ontario and Lucier Glove and Safety Products -- were evacuated.

Those buildings had minor damage, and the origin of the fire is still a mystery.

"Initial reports provided to us was it possibly being a train," says Andrea DeJong, a deputy chief with Windsor Fire and Rescue Services. "We have nothing to substantiate that."

One man said he first noticed the flames right after a train went by. Investigators are trying to determine what happened.

"The train scenario is plausible," says DeJong. "It is plausible based on the grass, the multipple fires, same area. None of them at this point seem to be suspicious."

Provincial Road was closed down for several hours. It has since reopened.

No damage estimate has been released but it's been suggested the damage will total more than $500,000, at which point, the Ontario Fire Marshal will be called in to investigate.