The Drug Enforcement Administration (DEA) recently seized the sixth-largest amount of counterfeit fentanyl pills in U.S. history.

The DEA's Rocky Mountain Field Division announced on Nov. 17 the seizure of 1.7 million counterfeit fentanyl pills and 12 kilograms of fentanyl powder (capable of 6 million pills) from a storage unit in Highland Ranch, Colorado, a suburb of Denver. The seizure is the largest one-time seizure of counterfeit pills in Colorado history, according to the DEA.

Colorado's Douglas County Sheriff's Office was notified of the storage unit's contents when it was purchased by a winning bidder, according to the DEA.

"This played out like an episode of a TV show," David Olesky, DEA Rocky Mountain Field Division special agent in charge, said in a news release.

The registered owner of the storage unit is already in federal custody as the seizure is connected with an ongoing DEA and Colorado Bureau of Investigation case. The DEA did not provide more information about the case when contacted by USA TODAY on Nov. 18.

What are counterfeit fentanyl pills?

Counterfeit pills are fake medications that contain different ingredients than the intended medication, according to the DEA. The pills look nearly identical to real prescriptions like Xanax and Adderall.

In the case of counterfeit fentanyl pills, the medication capsule contains fentanyl powder.

Where do counterfeit pills come from?

Per the DEA, most counterfeit pill production occurs in China, Mexico and India. But in recent years, more have been made in the U.S. The pills are popularly sold on social media and internet marketplace.

Greta Cross is a national trending reporter at USA TODAY. Story idea? Email her at gcross@usatoday.com.

This article originally appeared on USA TODAY: 1.7 million counterfeit fentanyl pills seized in Colorado storage unit