Firefighters are investigating how a pickup truck's interior started on fire, causing the driver of the truck to lose control and veer across all six lanes of I-15 early Monday morning.

According to the Davis County Sheriff's Department and the Utah Highway Patrol, the fire started in the interior of the 1979 Toyota pickup while the driver was northbound on I-15 just north of Beck Street about 3 a.m. Monday.The driver went off the right side of the highway, then veered left, proceeded across the northbound lanes, through the median, and across the southbound lanes before crashing into the guardrail, UHP reported. No other vehicles were involved.

Two passersby stopped and pulled the victim from the burning truck and the crew of a passing ambulance also stopped to render aid, with sheriff's department paramedics responding.

The victim, whose identity has not been released yet, was taken to the University Medical Center burn unit, suffering from burns over about half his body, paramedics reported.

Investigators from the South Davis Fire District are examining the pickup to try to determine the cause of the fire.