A 4-year-old boy died early Saturday after being thrown from a vehicle and then crushed when it rolled on top of him.

Killed was:Austin Williams, 4, West Jordan.

Williams was asleep on the floor of the van his mother, Pamela K. Williams, 40, was driving. Scott D. Williams, 36, was also asleep on the floor of the van, and Jordan Williams, 6, was asleep on the back seat. The family's van was southbound on I-15 and pulling a small pop-up travel trailer, Utah Highway Patrol Sgt. Kevin Olson said.

Pam Williams apparently fell asleep while driving and the car drifted off the right side of the interstate about 7:30 a.m., Olson said. She awoke suddenly and tried to get the van back on the road, but it careened into the median and rolled, ejecting her small son and the family dog. The van came to a stop in the lefthand northbound lane of the interstate, Olson said.

Austin Williams was pronounced dead at the scene. The family's cocker spaniel was also killed.

The other family members suffered minor cuts, bruises and abrasions and were taken to Valley View Medical Center in Cedar City, where they were treated and released.

No one in the family was wearing a seat belt, Olson said.