A mine worker has died following an “underground incident” reported early on Saturday morning in Jefferson County, Tennessee. The matter is currently under investigation, with the company fully cooperating with the Mine Safety and Health Administration, according to a spokesperson.

The Jefferson County Sheriff’s Office announced that the incident occurred at approximately 4:30 a.m. ET at the Nyrstar East Tennessee Young Mine, situated near New Market.

By early Saturday afternoon, authorities reported that emergency response teams had been deployed and that one employee was missing. Meanwhile, all other workers had been safely 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.