Three children and two adults were killed in Colorado on Sunday when an Amtrak passenger train collided with a minivan in Las Animas County in the southern part of the U.S. state, state police said.

The minivan, carrying six people, was traveling northbound on a county road when the driver of the van "failed to yield right of way" to the westbound train, the Colorado State Patrol said in a statement.

The driver of the van and four passengers were killed, including three children under the age of 18, said State Patrol Trooper Josh Lewis.

A girl was airlifted to a Denver-area hospital with serious injuries, the state patrol said. No crew or passengers on the train were injured, it said.

Amtrak said there were 286 passengers on the Chicago to Los Angeles line. The train struck a vehicle that was on the tracks at roughly 9:45 a.m. near Trinidad, Colorado, about four miles (6.5 km) east of the Amtrak Trinidad station.

The train in Sunday's Colorado incident struck the right side of the vehicle, which was not stopped on the tracks, police said. The driver and passengers were all wearing seat belts or restraints, they said.

Neither alcohol nor drugs were thought to have played a role in the crash, police said.

The victims have not been publicly identified, pending the notification of relatives.

Amtrak said some of its equipment was damaged but crews quickly made repairs and the train resumed its journey.

(Reporting by Keith Coffman in Denver; Writing by Eric M. Johnson; Editing by Sandra Maler and Paul Tait)