The cars, which were not believed to be carrying anything hazardous, derailed near the town of Paradise along the Clark Fork River, said Bill Brown, a dispatcher with the Sanders County Sheriff’s Office.

Firefighters and representatives of Montana Rail Link, which was operating the train, were responding and investigating what the cars were carrying, he said.

Photos posted on social media show some of the cars appearing to dip just into the river.

The train cars did not release any hazardous materials, Montana Rail Link said in a statement. The company said the cause of the derailment was being investigated.

“We are committed to addressing any impacts to the area as a result of this accident, prioritizing the safety of our employees and the public, and understanding the reasons for this incident,” the company said.

Montana’s U.S. Sens. Steve Daines and Jon Tester said in separate tweets that they were monitoring the derailment and were in touch with local officials.

Federal regulators and members of Congress are urging railroads to do more to prevent derailments after recent fiery wrecks involving hazardous chemicals in Ohio and Minnesota prompted evacuations.