KANNAPOLIS, N.C. -- They call it Operation Gray Death Nightmare.

The Kannapolis Police Department's Vice Narcotics Unit has been working hard over the past few months in the fight against the opioid epidemic in North Carolina. Officers followed up on dozens of overdose reports as well as tips from citizens.

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On Saturday, investigators announced 13 arrests in the investigation. Many of the suspects are from Charlotte, Concord, Salisbury, Rockwell and surrounding areas.

Tap here to see PHOTOS of suspects

"We want to make it clear that we will proactively investigate, identify, and arrest those individuals who choose to deal drugs in Kannapolis," said police.

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Seven other suspects at still at large.

If you have any information that may help investigators in Operation Gray Death Nightmare, call Cabarrus Area Crime Stoppers at 704-93-CRIME or visit the website.