DENVER (KDVR) — Police seized enough fentanyl in 2021 to kill Colorado’s population six times over.

Examiners haven’t yet released autopsy reports, but officials have attributed the overdose deaths of five cocaine users in a Commerce City apartment to fentanyl. Drug sellers increasingly mix the cheaply-produced synthetic opioid with common street drugs such as cocaine, heroin or methamphetamine.

The presence of fentanyl in Colorado is skyrocketing along with that of other drugs. Colorado State Police seized 151 pounds of the synthetic opioid in 2021 – more than three times the amount seized in the four previous years combined.

The U.S. Drug Enforcement Agency says a 2-milligram dose of the drug is lethal depending on the size of the drug taker. The 151 pounds seized in 2021 would be enough to give 34.2 million people a lethal dose.

Fentanyl arrived in Colorado almost overnight. CSP started seizing fentanyl in higher quantities beginning in 2019, when it seized 11 pounds. The patrol’s records say they seized none in the two years before that.

The drug’s lethality is concerning, but CSP has seized less fentanyl than other drugs. There was a dramatic increase in the volume of all drugs intercepted in 2021.

CSP found 2,161 pounds of cocaine, heroin, fentanyl and methamphetamine being smuggled in Colorado during 2021, nearly as much as the four previous years put together and more than three times the amount seized in 2020.

The biggest spike in seized drug volume came from methamphetamine. CSP intercepted 1,434 pounds of meth in 2021, more than half the total volume of seized drugs.

Cocaine was the second-largest volume of drugs seized with 359, followed by heroin with 217 pounds.