Authorities in Campbell County, Wyoming, told the Associated Press that the worker, identified by local Gillette media outlets as Derek Skyler Brux, was upset with a supervisor over working conditions.

Brux, who reportedly works for Rail Link, unhooked cars from the locomotive at about 9 a.m. on October 9, then commandeered the locomotive approximately 13 miles south on a main rail line before eventually crashing it into another train.

Police told the AP that the man, who was apprehended after the incident, faces preliminary charges that include reckless endangering and felony destruction.

No other injuries were reported. Peabody officials did not respond to a request for comment, damage estimates or details regarding the current operating status of the mine’s facilities.

The North Antelope Rochelle mine is the second largest coal mine in the nation.