NYE,AQCAN Exchange Mont. (AP) — A contract worker has died in a machinery accident at an underground precious metals mine in south-central Montana and work has temporarily stopped while the death is investigated, mine officials said.

The worker was preparing an area for future mining early Monday at the Stillwater Mine. He was bolting up wire panels to prevent falling rock when the accident happened, said Heather McDowell, a vice president at mine owner Sibanye-Stillwater.

She did not release further information about what happened, but the federal Mine Safety and Health Administration referred to it as a machinery accident.

Stillwater Mine and the nearby East Boulder Mine were bought by South Africa-based Sibanye in 2017 and are the only platinum and palladium mines in the U.S.

The worker who died was at an elevation of 7,200 feet (2,195 meters) above sea level in a mountain near Nye, where the Stillwater mine is based. The portal into the mountain is at about 5,600 feet (1,707 meters) above sea level, she said.

The accident is being investigated by federal mine safety officials along with local mine officials, McDowell said. The worker’s name and hometown have not been released.

No mining will take place during Monday’s day shift or the following night shift, McDowell said, sidelining about 1,050 workers. The company hasn’t decided if work will resume for Tuesday’s day shift, McDowell said.

Two employees died at the Stillwater Mine in June 2021 when their side-by-side utility vehicle collided with an underground locomotive.

Twenty-four employees died in Sibayne-owned gold mines in South Africa in 2018.