At least seven cars from a freight train tumbled into the Yellowstone River in Montana on Saturday after a derailment and a bridge collapse, causing asphalt and molten sulfur cargo to spill into the water, the authorities said.
Officials were investigating whether the derailment or the bridge collapse happened first, as well as how much of the cargo had spread into the river. What led up to the derailment was not immediately known, officials said.
The train cars, operated by Montana Rail Link, derailed around 6:45 a.m. local time as they headed west in Stillwater County, the county’s Disaster and Emergency Services Department said on Facebook.
Andy Garland, a Montana Rail Link spokesman, said no one was injured. Mr. Garland said that two cars were carrying sodium hydro sulfate, but neither had entered the water or been breached.
Three cars of hot asphalt and four cars of molten sulfur were in the river, officials said. Both substances were described as “slow moving.”
David Stamey, the chief of emergency services in Stillwater County, said by phone that both spilled substances solidify quickly in the water. That means the potential harmful effects to the environment could be limited, especially if the spread is restricted, he said.
Ten rail cars in total derailed, Mr. Stamey said. The derailment happened between Reed Point and Columbus, in an area about an hour west of Billings.
Referring to the cars, the Stillwater County Sheriff’s Office said that in a “great stroke of luck, none contained oil.” Officials said there was no expected hazardous materials impact to the towns in the county.
The Yellowstone County Disaster and Emergency Services Department said there had been no “negative impacts” as of early Saturday afternoon.
Video of the scene showed the collapsed bridge with rail cars peeking above the flowing water. It was not immediately clear when the bridge was constructed or when it was last inspected.
Mr. Garland said Montana Rail Link was “committed to addressing any potential impacts to the area as a result of this incident and working to understand the reasons behind the accident.”
In Yellowstone County, which has about 167,000 residents, officials said they planned to shut down water intake for the time it could take for any material to pass by Billings.
Similar measures were put in place at water treatment plants in Stillwater County, where about 9,000 people live.
Officials advised residents “to be aware of the situation and prepared to act should anything change.”
The derailment in Montana came about four months after a train carrying toxic chemicals derailed in eastern Ohio, igniting a fire that covered the town of East Palestine in smoke. That derailment prompted concerns about residents’ health and the environment.