(CNN) A federal grand jury has indicted pharmaceutical wholesaler Miami-Luken, two of its top former officials, and two pharmacists with conspiring to illegally distribute millions of prescription painkillers in some of the states hit hardest by the opioid epidemic, the Justice Department announced Thursday.

The indictment says the distribution of oxycodone and hydrocodone was "outside the scope of professional practice and not for a legitimate medical purpose," Benjamin C. Glassman, the US Attorney for the Southern District of Ohio, said in the indictment.

Miami-Luken, a drug distributor based in Springboro, Ohio, allegedly failed to report suspicious orders and exercise the care needed to prevent the drugs from being diverted from proper use.

The four individuals charged include Miami-Luken's former president and compliance officer and two West Virginia pharmacists, the release said. They were arrested Thursday morning.

"Today's arrests should be a wake-up call to distributors and pharmacists who are allowing opioid prescription pills to be illegally sold and dispensed from their facilities," said Drug Enforcement Administration Assistant Administrator John Martin.

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