Federal law enforcement officials announced a major drug bust Tuesday, seizing more than 100 pounds of fentanyl and arresting 22.

The takedown involved two Mexican drug cartels, but two kingpins remain on the loose.

The federal government has issued a cumulative $8 million reward for information leading to the capture of Johnny Hurtado Olascoaga, known as “Pez,” and his brother Jose Alfredo Hurtado Olascoaga, who goes by “Fresa.” They are both believed to be in Mexico, said Michael Herskowitz, who oversees narcotics and dangerous drug prosecutions for the U.S. Attorneys’ Office for the Northern District of Georgia.

“It is our hope that these multi-million dollar rewards will encourage people to come forward with what they know” about the brothers, he said, “both here in the United States and in cities and towns in Mexico.”

Some of the arrests involved a money-wiring operation in Gwinnett County that authorities said was sending drug proceeds to Mexico in small sums that would minimize attention. The practice, called “smurfing,” involves transactions below $10,000, a threshold for federal reporting.

Jae W. Chung, special agent in charge of the Drug Enforcement Administration’s Atlanta division, said the amount of fentanyl seized — 47 kilograms — would probably sell for around $1.5 million on the street and that it was enough to kill at least 23 million people. That’s more than two times the number of people in Georgia. (Two milligrams of fentanyl can be lethal depending on a person’s body size, tolerance and past usage, according to the DEA.)

“For Atlanta DEA, that’s probably the single largest seizure,” he said.

Chung said the investigation had been ongoing for years.

Herskowitz said the U.S. State Department had labeled the cartels as foreign terrorist organizations, which helped with the investigation

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