Sixteen people have been arrested and three million pills laced with fentanyl were seized in what federal prosecutors said Tuesday was the “largest fentanyl bust in DEA history.”

The operation, which spanned several states along in the West, “marks the most significant victory in our nation’s fight against fentanyl and drug trafficking to date,” Attorney General Pam Bondi said.

Among those arrested was a Sinaloa cartel leader, Heriberto Salazar Amaya, 36, a Mexican national, who was taken into custody in Salem, Oregon, Bondi said at a press conference. In February, the State Department designated the Sinaloa cartel as a foreign terrorist organization.

Asked whether any of those arrested would be deported to Mexico, Bondi said “I want them to stay in our prisons as long as possible.” “Most of these individuals, if convicted, will remain in American prisons, perhaps Alcatraz,” the attorney general added in reference to the shuttered California prison that President Donald Trump said he wants to reopen.