An estimated 254 pounds of the deadly synthetic opioid fentanyl was seized by U.S. Customs and Border Protection officials this past week. The drugs, which would have had a street value of $3.5 million, were found hidden in a secret compartment under the rear floor of a tractor-trailer delivering produce from Mexico to Arizona. Police dogs helped to alert officers to the presence of the drugs which also included 395 pounds of methamphetamine with a street value of $1.18 million.

Nogales CBP Port Director Michael Humphries stated, “It is said that a quarter-milligram, or the size of a few grains of salt, of fentanyl, which is a dangerous opioid, can kill a person very quickly.”

The number of fatal overdoses attributed to fentanyl continues to escalate around the U.S. Pop music legend Prince died in 2016 from accidentally consuming the opioid in counterfeit pills that looked like the narcotic analgesic Vicodin.

Fentanyl in its legal form is prescribed to provide relief to cancer patients suffering from unbearable pain at the end of their lives. But, the illegitimate version is being mixed with heroin for an extra kick as well as counterfeits of popular prescription drugs.

According to a report from the Federal Centers for Disease Control and Prevention, fentanyl is now the drug most often involved in fatal overdoses across the country, accounting for more than 18,000, or almost 29 percent, of the 63,000 overdose fatalities in 2016. Officials from the US DEA said that a majority of the fentanyl that is seized entering the US occurs around San Diego border stations, but more of it is being discovered at Arizona border crossings now.