Two Nebraska children are dead and four people are injured after a one-vehicle rollover crash on Interstate 80 near Laramie.

The Wyoming Highway Patrol says 23-year-old Edgar Carmona of Columbus, Neb., was driving eastbound with five passengers shortly after 9:30 a.m. Thursday when his pickup truck slid off the roadway and hit a guardrail. The highway patrol says Carmona's vehicle then hit a concrete bridge support and rolled several times.

The five passengers, all of whom weren't wearing seatbelts, were ejected from the vehicle: 12-year-old Sergio Carmona, 13-year-old Verania Carmona, 41-year-old Jose Carmona, 3-year-old Saul Carmona - all of Columbus, Neb. - and 30-year-old Rosa Lopez-Ramos of Vancouver, Wash.

Sergio Carmona was found dead at the scene. Verania Carmona was pronounced dead at Denver Children’s Hospital.

Edgar Carmona, Jose Carmona, Saul Carmona and Lopez-Ramos were taken to Ivinson Memorial Hospital in Laramie for treatment.

Troopers cited Edgar Carmona for driving without a driver’s license and failure to maintain a single lane of travel.

Investigators believe fatigue was a contributing factor in the crash.