GREAT FALLS, Mont. -- U.S. authorities have identified a Canadian man who was killed after his minivan struck a tractor-trailer that left the scene of the crash on Interstate 15 in northern Montana.

Sheriff Bob Edwards says 72-year-old Marvin Knutson of Swift Current, Sask., died late Saturday when his van hit a truck as it used an "authorized vehicle only" area to cross the median to enter a weigh station near Great Falls.

Investigators with the Montana Highway Patrol say the truck driver stopped briefly near the weigh station and then continued north on I-15.

The Great Falls Tribune reports officers are searching for the driver of the truck.

The truck was hauling two-by-four lumber and should have damage on the right rear side of the trailer.