The Gillette Police Department and the Campbell County Sheriff's Office responded to the Flying J truck stop off Highway 59 at the interchange with Interstate 90 on Monday morning.
Officers with drawn weapons were seen in positions behind their cars surrounding the truck stop.
Police were searching for a "person of interest" inside the building, Sheriff Scot Matheny said.
He added that while his office has responded to assist, it's a Police Department case and he deferred other questions to the GPD. Police are still working the incident and weren't available.
The building search has concluded, but it's not known whether anyone was found in the search.
Editor's note: This story has been updated to reflect that Sheriff Matheny did not say a dead body was found in the shower of the truck stop. That was a rumor that came into the News Record and through a miscommunication, we thought the sheriff had confirmed that information.
This is a developing story and will be updated as more information becomes available.