Boise (Idaho): Several children were injured when a school bus rear-ended another while picking up students on a rural highway in eastern Idaho on Monday morning, authorities said.

Four students and both bus drivers were taken to hospitals, with one child airlifted to Utah for treatment, the Idaho State Police said. Seventeen students were on board the two buses at the time, while a few waiting to board escaped unhurt.

Idaho State Police Sergeant Benjamin Foster said the second bus was travelling at “a considerable amount of speed” around 7.15 am in low light conditions during the twilight-dawn period. Three students treated at a nearby hospital reportedly sustained non-life-threatening injuries, including broken noses. Police did not release updates on the condition of the child airlifted.

A photo released by authorities showed the front of one bus crumpled, with the engine compartment exposed and warning lights still illuminated.

The collision occurred on State Highway 25 near the farming town of Paul, about 155 miles southeast of Boise and an equal distance northwest of Salt Lake City, Utah.

The Minidoka County School District said on Facebook that it is “cooperating fully with authorities as the incident is reviewed,” adding that “student safety is always our top priority.”

The crash remains under investigation.