JONESBURG, Mo. (AP) — Missouri authorities say a man clung to the hood of tractor-trailer for miles on a St. Louis-area freeway before being hit by another semi rig while running in and out of traffic.

The Missouri State Highway Patrol says it’s unclear why 20-year-old Darryl Boyle of O’Fallon, Missouri, was walking on Interstate 70 west of St. Louis on Tuesday evening or why he climbed onto the tractor-trailer.

Doyle died at a hospital shortly after being hit in a westbound lane near Jonesburg.

Patrol Sgt. Al Nothum says that after slowing traffic to a crawl, Boyle grabbed the side mirror of an eastbound tractor-trailer, climbed onto the hood. Doyle rode atop for miles before jumping off and was fatally hit by another semi rig as authorities converged on him.