About 25 train carriages have derailed in north-western Montana, with no injuries or evacuations reported, authorities said.
The carriages, which were not believed to be carrying anything hazardous, derailed near the town of Paradise along the Clark Fork River, a police spokesman said.
Photos posted on social media show some of the cars appearing to dip into the river.
The firm added: “We are committed to addressing any impacts to the area as a result of this accident, prioritising the safety of our employees and the public, and understanding the reasons for this incident.”
Federal regulators and members of US congress are urging the railways to do more to prevent derailments after recent fiery wrecks involving hazardous chemicals in Ohio and Minnesota prompted evacuations.
