CHICAGO - Four people have been charged in the gang-related Chicago shooting involving an assault-style rifle that injured 13 people in a city park, including a 3-year old boy, police announced today.

"As of right now we have four offenders charged in this shooting, including the man who fired that military grade weapon and the man who supplied that military grade weapon," police superintendent Garry McCarthy told a press conference.

Tabari Young, 22, Bryon Champ, 21, Brad Jett, 22, and Kewane Gatewood, 20, were all charged with three counts of attempted murder and aggravated battery with a firearm, McCarthy said.

Young, police said, was the main shooter in last Thursday's incident in the Back of the Yards neighborhood on the city's South Side. Champ, who police said also fired a gun, is a documented gang member who was convicted of a felony - unlawful use of a weapon by a felon - last year, but was only sentenced to boot camp, according to police. Gatewood, authorities said, supplied the military grade weapon and Jett participated as a lookout, McCarthy said.

Chicago Police Dept.

McCarthy said that Champ was the "main player" in the incident, citing that Champ suffered a graze wound to his leg in a shooting earlier in the day that led to the retaliatory shooting at the basketball court in the Back of the Yards.

"If Bryon Champ is not on the street - as he shouldn't have been - this incident likely does not occur," McCarthy said.

"If Champ is not on the street, there's no retaliation because there's no incident," he added. "This individual was the victim of gun violence and then became the offender of it."

Among the wounded was 3-year old Deonta Howard, who suffered a gunshot wound to his ear. Howard has undergone plastic surgery and is expected to recover.

Thursday's incident was only the latest in a string of tragic shootings in the city. Earlier this year 15-year old Hadiya Pendleton was shot and killed only days after performing at President Obama's inauguration.

McCarthy today reiterated his calls for stricter gun laws to help crack down on the city's gun violence problems.

"Illegal guns and weapons designed for war do not belong on the streets of Chicago," he said.

In another grisly incident this week, a mother and her daughter were found strangled in a burning car in a nature preserve near the city. The bodies of Mary Ann Urban-Danno, 51, and her mother Theresa Urban, 79, were found in a Chrysler PT cruiser in Palos Park, a suburb around 20 miles southwest of Chicago. The Cook County Sheriff's Office said today that first degree murder charges have been filed against Mary Ann's husband Robert Danno, 50, and Jose Fernando Martinez-Hernandez, 24.

The fiery car was first reported to authorities late Saturday night. Authorities allege that Urban and Urban-Danno were strangled and then put in the PT Cruiser, which the men then set on fire.