The Northfield Police Department is warning that three recent overdoses in the city were tied to a powerful and sometimes deadly synthetic opioid.

While the purchasers thought they were buying “Oxy” – a common nickname for the pain relievers Oxycontin, Oxycodone, or Percocet, lab results from the Minnesota Bureau of Criminal Apprehension showed the pills in question contained Carfentanil, which is up to 10,000 times more potent than morphine.

Investigators say the pills had been manufactured to look like real Oxycodone 30 mg pills.

They also say they have been associated with thousands of overdose deaths around the United States.

They’re telling people who purchased the illegal drugs not to take them, and add that if anyone is in possession of pills like these takes them to the police department for testing they will not be prosecuted.