TREMONTON, Box Elder County — A fire at a hay plant has caused between $8 million and $10 million in damage, fire officials said Thursday.

The blaze broke out at Bailey Farms International hay plant, 4600 N. Iowa String Road, Wednesday night and continued to burn Thursday.

The fire exited the building and spread to a propane tank. The propane tank exploded and ignited piles of hay. Towering flames burned throughout Wednesday night.

Firefighters could not enter the building to suppress the blaze because the buildings were structurally unsound, according to Box Elder County Fire Marshal Corey Barton. The fire was not near any residences, and fire officials planned to let the fire burn itself out.

"It's in a very safe area so we're just going to monitor it and let it go," he said. "It's going to burn for a long time."

Barton said that due to the extreme size and intensity of the fire, it is unlikely a cause will be determined.

— Morgan Jacobsen