(NBC News) — Two workers were found dead Sunday at a waste recycling plant in North Carolina, authorities said.

The cause of death for the workers, who were employed at Valley Protein Inc.’s location in Fayetteville, was not immediately known. The Cumberland County Sheriff’s Office did not identify them.

A sheriff’s spokeswoman said the pair were found unresponsive Sunday shortly after authorities were called to the plant at 1:32 p.m. Major crimes detectives were investigating, authorities said.

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