JEFFERSON COUNTY, Tenn. (WATE) — A mine employee is dead after an “underground incident” was reported early Saturday morning in Tennessee’s Jefferson County. An investigation is ongoing, and the company is cooperating with the Mine Safety and Health Administration, a spokesperson said.

At around 4:30 a.m. ET, the Jefferson County Sheriff’s Office said the Nyrstar East Tennessee Young Mine, located near New Market, reported an underground incident.

Early Saturday afternoon, the sheriff’s office reported that response teams were activated and one employee was unaccounted for. All other employees had been evacuated from the mine.

The sheriff’s office said search and rescue efforts were underway.

On Sunday, a spokesperson for the mine said, “We extend our deepest sympathy and are providing support to the family, friends and colleagues of the deceased.”

According to Nyrstar’s website, the company employs approximately 440 people at its three East Tennessee zinc mines. The website added that the Young mine site is also where ore from the mines is processed into zinc concentrate.

No additional details were immediately available.