A drug bust last year was hailed as the largest fentanyl bust in U.S. history—254 pounds seized at an Arizona border crossing.

The seizure came as the scourge of fentanyl continues to fuel the opioid epidemic, ravaging communities across the U.S. while killing tens of thousands of people.

"Fentanyl also continues to be a tremendous problem, contributing to 68,000 overdose deaths in the United States in 2018," Mark Morgan, acting commissioner of U.S. Customs and Border Protection told Congress in November. He said CBP's seizures of fentanyl rose by 30 percent in fiscal year 2019, totaling 2,770 pounds.

Fentanyl comes from China. Often it is smuggled into the U.S. from Mexico by drug cartels involved in a violent war with Mexican police and military forces.

The historic 254-pound bust was just one of a half-dozen big fentanyl busts recorded by law enforcement in recent years, a tally shows.

These six busts have led to the seizure of some 818 pounds of fentanyl--enough to kill 229 million people, according to authorities.

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Here’s the list:

Nogales, Ariz., 254 pounds

A Border Patrol K-9 at the Nogales border crossing sniffed narcotics when an 18-wheeler transporting cucumbers from Mexico came through for inspection on Jan. 31, 2019.

Further inspection discovered nearly 254 pounds of fentanyl worth $3.5 million in a secret compartment, enough to kill 115 million people.

It was the largest fentanyl seizure ever at a U.S. border crossing.

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“This past weekend our CBP officers were able to stop an enormous amount of these deadly narcotics from hitting our streets,” Nogales Area Port Director Michael Humphries said.

The truck was also carrying 395 pounds of methamphetamine.

Trucker Juan Antonio Torres-Barraza, a 26-year-old Mexican national, told agents he didn’t know he was hauling narcotics.

He has since pleaded guilty.

Queens, New York City, 140 pounds

Federal drug agents and police raided an apartment in Kew Gardens, Queens and seized 140 pounds of fentanyl on Aug. 1, 2017, enough to kill 32 million people.

At the time, it was the nation’s largest seizure of pure fentanyl, officials said.

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Another 48 pounds of fentanyl mixed with heroin was also seized.

The 188 pounds of drugs were worth about $30 million.

Kearney, Neb., 118 pounds

A Nebraska State Trooper stopped a tractor-trailer on I-80 on April 26, 2018, and, after conducting a search, seized 118 pounds of fentanyl worth $20 million, enough to kill 26 million people.

The seized opioid was hidden in a false compartment of the vehicle.

The trucks two occupants Felipe Genao-Minaya, 46, and Nelson Nunez, 52, both of Newark, N.J., were arrested on drug trafficking charges.

The trooper who pulled over the truck described Geano-Minaya as “nervous and shaking visibly in the truck” as he questioned him.

Charges against the two men are still pending.

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Philadelphia, Pa., 110 pounds

At the port of Philadelphia, border agents seized 110 pounds of fentanyl worth $1.7 million on June 28, 2018, enough to kill 24 million people.

The fentanyl was found in a shipment of iron oxide from China.

A Border Patrol K-9 alerted agents after going through barrels of iron oxide barrels and detecting narcotics.

"Opioids, including fentanyl and its analogues, are a serious public health concern, and the importation of vast amounts of this deadly synthetic chemical compound is a national security threat,” Casey Durst, CBP Director of Field Operations in Baltimore said after the seizure.

North Bergen and Willingboro, N.J., 99 pounds

New Jersey State Police detectives grabbed 88 pounds of fentanyl after observing a drug transaction in a commercial parking lot in North Bergen on June 28, 2017.

Detectives swooped in as the fentanyl was being transferred from a tractor-trailer to the trunk of Mercedes-Benz.

The bust led to another seizure the next day of 11 more pounds of fentanyl at a home in Willingboro.

The fentanyl was enough to kill 18 million people, investigators said.

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Two men were arrested: Jesus Carrillo-Pineda, 31, of Philadelphia and Daniel Vasquez, 28, of Somerton, Ariz.,

After pleading guilty, Carrillo-Pineda was sentenced to 10 years in prison and Vasquez was sentenced to six years.

The seizure of the 99 pounds drove home “the scope of the problem we face in New Jersey with this highly lethal opioid,” Director Elie Honig of the Division of Criminal Justice said.

San Diego County, Calif., 97 pounds

After stopping a rented vehicle in San Diego County on Nov. 30, 2016, DEA agents seized 33 pounds in the trunk.

After arresting Anna Baker, the agents obtained a search warrant to search her home and seized another 64 pounds of fentanyl.

The 97 pounds of fentanyl was enough to kill 14 million people.

Two others Jonathan Ibarra, 45, and Hector Fernando Garcia, 46, were also arrested.

All three pleaded guilty and sentenced to prison.

Baker, the daughter of a former mayor of Lemon Grove in Southern California, was sentenced to four years in prison two years ago.

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"I made a terrible, huge mistake," Baker said, the San Diego Union-Tribune reported. "I'm very ashamed about what I did."