SAN FRANCISCO >> A drug bust by federal agents and San Francisco police netted 12.5 pounds (5.7 kilograms) of the deadly narcotic fentanyl and charges against 18 people suspected of supplying drug dealing operations in the city’s troubled Tenderloin neighborhood, authorities announced this week.

Federal prosecutors charged eight people with conspiracy, each in connection with one of two drug trafficking organizations based in the San Francisco Bay Area that distributed fentanyl and other narcotics shipped in bulk from Southern California, officials said Tuesday.

San Francisco’s Tenderloin is a diverse neighborhood that has families with children living in apartments, homeless people, theater venues and government buildings including City Hall and the U.S. Attorney’s office. It’s also a neighborhood where dealers brazenly peddle drugs in the open and users shoot up the drugs in public stairwells.

“The staggering loss of life we’ve seen due to drug overdoses is a public health calamity San Franciscans haven’t witnessed since the height of the AIDS crisis,” San Francisco Police Chief Bill Scott said in a statement.

Fentanyl is a cheap and potent opioid that has fueled overdose deaths in San Francisco and around the U.S.

Police have said increased fentanyl trafficking is also driving a sharp increase in gun violence in the neighborhood.