A Montana Rail Link official says a freight train has derailed 4 miles east of Superior.
Spokeswoman Lynda Frost says 23 cars of the 66-car train bound for Laurel derailed early Wednesday along a steep embankment above the Clark Fork River.
She says four of the cars are partially submerged in the river.
The train was carrying a variety of commodities and had 19 empty cars. Frost says the only spillage from the derailment is cedar chips and lumber.
The cause of the derailment is under investigation.
Heavy equipment has arrived to begin removing the wreckage. Frost says the remote and steep terrain will make the cleanup challenging.
Frost says about 20 trains travel that line each day and will be diverted to another route.