Several train cars fell in the Yellowstone River after a bridge collapse near Columbus, Montana, U.S., June 24, 2023. （Photo：CFP）

A train derailment in the U.S. state of Montana caused a bridge across the Yellowstone River to collapse on Saturday morning, landing multiple rail cars carrying hazardous materials in the water, according to CNN.

Montana Rail Link, the company operating the train, said in a statement that "several hazmat cars" plunged into the river. No injuries have been reported among the train crew, it added.

The rail cars were carrying asphalt and molten sulfur, substances that quickly solidify when they come in contact with cooler temperatures, the company said.

Two cars transporting sodium hydro sulfate, an acid salt, did not enter the water, and initial air quality assessments indicate the chemical was not released from the cars, Montana Rail Link said.

Multiple local, state and federal agencies were coordinating the response and working to determine what caused the derailment. Authorities were "unsure" what happened first – the derailment or bridge collapse, local media reported.

"Local fishing accesses will be closed. Water treatment plants, irrigation districts, and industrial companies are taking appropriate precautions," the Yellowstone County Sheriff's Office said.