The shooting took place at about 2 a.m. at the South Shore Cultural Center, officials said. Many victims were taken to nearby hospitals, police said.
An hour after the shooting, it was unclear what led to the shooting.
The suspect walked into the center where a “large amount of people were partying,” and “somebody began shooting,” Chicago Police Department Chief Communications Officer Anthony Guglielmi said.
A law enforcement official said the shooting appears to be gang-related.
The rampage comes amid a troubling uptick in gun violence in Chicago, where roughly 600 people have been shot since the beginning of the year. More than 700 have been killed in the same period.
“This has been an extremely violent year and it continues right now. It’s alarming,” Mayor Rahm Emanuel said at a news conference.
Hours after the shooting, “a vigil” took place outside of the center, which serves children as young as 5, the Chicago Tribune reported. Community activists, including Rev. Michael Pfleger, Father Michael Pfleger, handed out teddy bears to mourners.
“We need to clean up our neighborhood,” Pfleger said. “And let’s just put them to bed by providing hope for them. … A graveyard in the middle of our neighborhood is very ugly, and it needs to change.”
Pfleger said “our hearts go out to everybody.”
According to Guglielmi, 23 victims were taken to local hospitals, and another four were taken to undisclosed hospitals outside of Chicago.
Eleven of the wounded were in “critical condition,” Guglielmi said.
Members of the department gave the following updates on those wounded in the attack:
Five were transported to Advocate Christ Medical Center in Oak Lawn.
Four were taken to Northwestern Memorial Hospital.
Three were taken to Advocate Trinity Hospital.
Two were taken to St. James Hospital in Chicago.
Four were taken to other hospitals outside of Chicago.
Police cars filled the roads throughout the neighborhood as officers investigated.