Four men have been charged with attempted murder for their role in Thursday’s shooting in Chicago’s Cornell Square Park, which injured 13, including a three-year-old boy, NBC Chicago reported.

Tabari Young and Brad Jett, both 22, were charged on Tuesday with three counts of attempted murder and aggravated battery with a firearm, along with Bryon Champ, 21, and Kewane Gatewood, 20, who were charged on Monday, the report said.

The current charges against the four men are preliminary, and Garry McCarthy, Chicago Police Superintendent, told the media that more charges will be brought against the men as the investigation progresses.

"[The investigation is] Not even close to being finished," McCarthy was quoted by NBC Chicago as saying.

According to reports, the mass shooting stemmed from a gang conflict, which took place earlier last week. Reportedly, Champ was hurt during a gang-related shooting last week and decided to take revenge against the rival gang by indiscriminately opening fire at Cornell Square Park, which they considered to be the rival gang’s turf.

Champ was aided by Young and Gatewood, who according to Chicago Tribune, supplied the AK-47-style rifle used in the shooting while Jett acted as a lookout.

Announcing the charges against the men, McCarthy told a news conference that Champ had a felony charge against him for unlawful use of a weapon in July 2012 and sentenced to boot camp. McCarthy noted that if he had been appropriately punished, Thursday’s shooting would not have occurred.

"Illegal guns drive violence," McCarthy was quoted as saying by Chicago Tribune. "If we don't provide real punishment for the criminals who carry them, what message is it that we're sending? Where are the priorities of the criminal justice system?”