The sweep was the fifth time Chicago police have worked with the Federal Bureau of Investigation on gang sweeps, but the first time they teams focused on weapons trafficking.
A combined federal and state investigation into street gangs and those who provide them with weapons has resulted in charges against more than two dozen people and more than 60 guns off the streets.
What they found was that streets gangs were just as adept at moving guns as they are selling drugs.
While none of the guns have been specifically linked to attacks on police officers, Chicago police Supt. Jody Weis said he's glad to see the FBI's emphasis move from drugs to guns.
"Our guys are anxious to pursue anything that will take guns off the street," Weis said. "It's highlighted now, based on the three murders of police officers, and if you go back to Alex Valadez, who was murdered on June 1, 2009, we have had four Chicago police officers killed by acts of violence through the use of weapons in a little over a year."
Officers Thomas Wortham, Thor Soderberg and Michael Bailey have been killed in the last two months.
The undercover transactions often happened in public places, like the Home Depot parking garage at Armitage and Cicero, and a gas station near Kilbourn and Fullerton, authorities said.
In perhaps their boldest move, agents recruited some of the gang members to conduct what they were told was an armed rain on a drug stash house that never actually existed.
"An undercover convinced them that there was a drug house, convinced them and asked them whether they were willing to raid it. They made those statements that... they'd shoot people for free, they'd shoot them for cocaine to convince the undercover that they're the ones who should be given the job of robbing this house," said Federal Prosecutor Patrick Fitzgerald.
So far, 25 Chicago-area residents have been charged. Twenty-two were arrested Tuesday and Wednesday at various locations in and around Chicago by members of the FBI's Joint Task Force on Gangs, as well as Chicago Police. Three others -- Samuel Munoz, Carlos Vigneri and Guillermo Zamudio Jr. -- remain at-large and are considered fugitives.
Thirteen were charged in one of seven separate criminal complaints filed earlier this week in U.S. District Court with violating federal drug and firearms laws. Six of the complaints charged one or more defendants with violating federal weapons laws while the seventh charged four defendants with conspiring to possess multi-kilogram amounts of cocaine.
The remaining 12 suspects were charged in separate criminal complaints filed by the Cook Count State's Attorney's office with unlawful sale of a firearm and unlawful use of a weapon. One of the state defendants also faces separate drug charges.
The confiscated weapons are now being traced to see if they've been used in any crimes.
"If you look at the amount of weapons... we can only imagine what they were going to be used for," said Cook County State's Attorney Anita Alvarez.
The weapons are alleged to have been purchased in neighboring states and sold for $300 to $1,000.