The officers reportedly came across a shooting in progress at First and Court streets just after 10:30 p.m. Thursday.
The suspect ran off as they arrived, and officers fired several shots, but the gunman apparently escaped.
The victim of the shooting was rushed to Trinitas Hospital, where he was pronounced dead.
He appeared to have been shot in the head.
No officers were injured. The shooting is under investigation by the Union County Prosecutor's Office.
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