They sold bags of cocaine and heroin, some laced with fentanyl, for $10 bucks per bag, authorities said.
WATCH: US Attorney John Lausch announces charges in drug trafficking investigation
"These are drugs that are packaged and bundled in a particular way for someone to be out there on the street selling it to customer after customer after customer," said U.S. Attorney John Lausch.
In a nearly 70-page complaint, authorities charged 10 alleged members of the Four Corner Hustlers, some with nicknames that include "Peanut" and "D-Nice" with federal drug conspiracy.
Aurora's Nathaniel Evans, 38, directed the drug trafficking operation and supervised the three open-air markets, which were located in the 3900 block of West Jackson Boulevard, 3900 block of West Van Buren Street and 4000 block of West Maypole Avenue, according to the federal charges.
Four others allegedly worked as "shift managers, overseeing drug sales at the illegal markets at various times of the day. That group includes 24-year-old Jarelle Jones of Forest Park and Chicagoans Marquis Jones, 29, Joseph Williams, 31, and Dornell Williams, 34.
Chicago's Devontay Logan, 27, picked up narcotics from suppliers, delivered them to the Jackson Boulevard location and collected proceeds after the sales, the charges alleged. Three others allegedly worked as street-level dealers, while the charges accuse 40-year-old Maurice Bell of obtaining narcotics for sales at the Maypole Avenue location. That group includes Chicagoans Teremius Webb, 25, Antonio Fletcher, 40, and Kyle Linton, 25.
The joint federal and local investigation began in February of last year and included wiretaps, covert surveillance and narcotics purchases by undercover officers.
"We leveraged our resources and conducted a thorough investigation which led to multiple arrests and seizures," said Homeland Security Investigations Special Agent-In-Charge Angie Salazar.
Investigators said in addition to drugs, they recovered several weapons, including a MAC-10 submachine gun, and hundreds of rounds of ammunition, allegedly used to protect the operation.
"Families and residents of all ages, from school children to senior citizens, were impacted and intimidated on a daily basis," said First Dep. Supt. Eric Carter of the Chicago Police Department.
The charges come months after the gang's longtime leader was convicted of racketeering conspiracy connected to multiple murders. In addition to the ten men charged federally, another 21 people face state charges in connection with this investigation.