Two Nevada men were killed Saturday in a traffic accident and an Arizona motorist died of an apparent heart attack while at the wheel, the Utah Highway Patrol said Sunday.

DEAD:John DeGiovanni, 25, Las Vegas, Nev.

John Hyson, 41, Las Vegas, Nev.,

John Vala, 76, Clarkdale, Ariz.

DeGiovanni and Hyson were identified as the men killed when the pickup truck DeGiovanni was driving ran a stop sign and crashed into a semitrailer truck about 35 miles west of Cedar City at the intersection of SR 18 and SR 56, a dispatcher said.

Hyson's son, Aaron, 10, was listed in critical condition Sunday at Valley View Medical Center. He was transferred to a Nevada hospital Sunday night, according to a Cedar City hospital spokeswoman.

And, in a separate incident, John Vala, 76, Clarkdale, Ariz., died of an apparent heart attack while driving south on I-15, about 20 miles north of Beaver, the dispatcher said. His vehicle ran through a center divider, across oncoming traffic lanes and through a fence, the UHP said.

His 74-year-old wife, Dorothea, was wearing a seat belt and escaped injury, the dispatcher said.