Officers responded to a credible threat at the General Motors plant in Burton Tuesday night.
It happened about 9:30 p.m. on Sept. 15.
Police said the threat came from an employee of the plant and they never showed up to work.
Law enforcement and management knew the individual was not in the building at the time because of the strict protocols to enter the facility.
Extra police patrols were sent out to the area that night.
Officers are still searching for the employee behind the threat.
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