(CHICAGO) -- Two men considered "persons of interest" are being questioned by Chicago police in connection with a playground shooting that wounded 13 people, including a 3-year-old boy.
The shooting outraged Chicago, which has seen a spate of murders this year.
Police spokesman Adam Collins told ABC News that investigators are talking to "two persons of interest" about the shooting.
The shooting occurred around 10 p.m. last Thursday at a basketball court in a park in the city's Back of the Yards neighborhood. At a press conference Friday, Police Superintendent Garry McCarthy said the incident appeared gang-related and the shooter used an assault rifle with a high capacity magazine.
Among the injured was 3-year-old Deonta Howard, who suffered a gunshot wound to his ear. His grandmother, Semehca Nunn, said Friday that Howard was recovering after surgery and was "doing better."
Nunn, whose son was killed a week earlier, pleaded for the violence that has riddled Chicago to cease.
"It's got to stop," she said. "I'm going to be out here every day, protesting, walking these blocks, my neighborhood especially. It's got to stop because y'all are hurting innocent people -- kids."
In the wake of the shooting, McCarthy emphasized the need for stricter gun laws.
"Illegal guns drive violence," he said. "Military type weapons, like the one we believe to have been used in the shooting, belong in a battlefield, not on a street or in a corner or in a park in Back of the Yards."
Thursday's incident is 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.
Copyright 2013 ABC News Radio