Fred L. Waller, chief of the Chicago Police Department's patrol bureau, said ShotSpotter technology, gunshot detection software operating across the city, detected and recorded the shooting around 12:35 a.m.

Waller said the shooting was an "isolated incident." He said a dispute occurred inside a South Side home when shots rang out. As people fled the house, another shooter was picking people off from an outside location. 

Waller said three separate types of shell casings were found in and around the home.

"From outside, definitely there was two different shooters," Waller said at a presser Sunday morning. "It looked like they were just shooting randomly at people as they exited the party."

He said two people are being questioned in connection with the shooting. One of the suspects was carrying a revolver when detained. 

A 29-year-old woman who declined to give her name to the Chicago Tribune, said, "It's real f---ing sad. Your kids can't grow up, you can't do anything. This is what our life is going to be about [refering to inner-city chaos]." 

Citywide, homicides have been trending lower for the past four years.