FARMINGTON -- Jonathan Owens saw the flames in his rearview mirror and knew he needed to pull over fast.
Owens, 33, was driving a semitrailer from Bear River to Delta, carrying 26 one-ton bales of hay.
"There were lots of flames," Owens said. "They were in the deck (of the truck) and on the tires."
Owens managed to separate his truck from the trailer carrying the burning hay before firefighters from Kaysville and Farmington arrived.
The 911 call for the burning hay on southbound I-15 near Farmington came in at 11:30 a.m. Friday. Crews were on the scene for at least an hour and they closed the right lane. Traffic was backed up for about three miles.
Kaysville Fire Chief Brett Larkin said that when his crews arrived, the flames "were not really big, but there was a lot of smoke. It was a smoldering fire."
Larkin said hay fires can be difficult because the bales are compacted. Firefighters have to separate the bales and look for hot spots, then water them down.
A slight breeze was also a concern, Larkin said.
"You have to rake and dig through (the hay) or it will start back up later," Larkin said.
Owens said he thinks the twine that held a bale together broke and fell on the exhaust pipes, which started the fire.
Utah Highway Patrol Trooper Taylor Van Houten said hay fires on semitrailers do happen, but usually it is because the hay is still green and will combust.
"But this is not what happened this time," Van Houten said.
Larkin said the truck and trailer were moved to the nearest rest stop because the lines that control the lights had been damaged.
No cost estimate of damage to the hay and truck was available.