A grand jury this week indicted 11 people accused of using UPS to traffic narcotics and counterfeit vaping pens across the country.

Homeland Security Investigations special agents in Arizona and Tucson police arrested the 11 suspects in late November after an investigation into suspected drug trafficking and money laundering.

The federal agency said that U.S. agents and local police began investigating after the Tucson department discovered drug traffickers were using the United Parcel Service to ship narcotics to the eastern U.S., then transport bulk currency back to Tucson. A dozen other agencies and UPS also helped investigate.

Four UPS employees were among those arrested on warrants over the past two weeks. The other suspects were arrested in Arizona’s Pima County, where Tucson is located.

Authorities seized bulk currency, equipment used to make illicit drugs, 50,000 counterfeit THC vape pens and unspecified other kinds of narcotics. Three vehicles were also seized.