YUMA, Colo. -- A Yuma County School bus rear-ended a tractor-trailer Thursday morning, sending the bus driver and four students the hospital with injuries.

The crash occurred at 7:40 a.m. at the intersection of Colorado Highway 34 and Yuma County Road H, east of Yuma.

According to the Colorado State Patrol, the black Freightliner was westbound on Colo. 34 and was making a right turn when the yellow school bus, also traveling westbound, struck the rear of the truck.

The bus driver, 58-year-old Bunnie Hardy, of Yuma, had to be extricated from the wreckage and was transported to the Yuma District Hospital, along with the 12 students on the bus.

Four students sustained minor injuries and received treatment, while eight children were unhurt and released from the Yuma District Hospital and clinic without treatment, the CSP said. The student's injuries were listed as minor to moderate. The bus driver's injuries were considered moderate.

The students' ages range from 5 years old to 16 years old. Alcohol, drugs and speed are not suspected as contributing factors, investigators said.

The Colorado State Patrol's Accident Reconstruction Team was sent to the crash location, 115 miles northeast of Denver.