U.S. Customs and Border Protection says agents have made the largest fentanyl bust in history, seizing a quantity of the drug large enough to kill 57 million people.

First reported on "Tucker Carlson Tonight," Fox Business correspondent Hillary Vaughn said the seizure occurred January 26 when a tractor-trailer was stopped as it came over the border crossing in Nogales, Arizona.

Vaughn said 114 kilograms of fentanyl, 179 kilograms of methamphetamine and one kilogram of fentanyl pills were found under the floor of the trailer.

The smuggler, a Mexican national, was arrested. Vaughn said the driver attempted to smuggle the drugs across the border at a legal port of entry.

The driver was part of the DHS Fast and Secure Trade (FAST) program, which allows trusted travelers to cross into the U.S. with expedited screening as long as they pass background and other checks. The CBP planned a press conference for Thursday to announce the bust. 

Authorities have said that illicit fentanyl - often mixed with heroin to make it more potent - has become the biggest source of fatal overdoses in the United States. 

Earlier this month, authorities in Chico, California, said a "mass overdose" at a home left one person dead and 12 hospitalized, including four in critical condition. Police said they suspected fentanyl was the cause of the overdoses.