Idaho State Police investigators are still trying to figure out what caused a semi truck driver to lose control of his rig early Wednesday on the westbound lanes of Interstate 84 west of Caldwell, which caused another truck behind it to wreck and spill fuel on the highway.

It took emergency crews several hours —  from about 4:30 a.m. to 7:30 a.m. — to investigate the crash and clear debris and fuel from the road, which resulted in traffic headaches for drivers because the right lane of I-84 was closed during cleanup, according to ISP reports.

Investigators say 29-year-old Westley Bullock of Pocatello lost control of a semi truck hauling two coal trailers and drove off the side of the road, where the semi hit the guardrail and came to a stop on the right shoulder around 4:30 a.m.

Investigators say 63-year-old Leland E. Everhart of Payette was driving a semi truck hauling Coca Cola products behind Bullock’s truck when Everhart ‘s truck drove over the broken guardrail, which was on the road. That debris punctured the fuel tank and damaged a tire, which caused Everhart to pull the truck over to the right side of the road, according to reports.

Caldwell Fire crews were able to contain the fuel leak. Neither man was badly hurt in the wreck. ISP officials say it appears that weather, alcohol use, and drugs were not a factor in what happened.

Neither driver had been cited as of 1:45 p.m.