Thirteen people, including a 3-year-old boy, were shot late Thursday in a Chicago park, local police said.
The incident took place at around 10:15 p.m. (0315 GMT) at a South Side Chicago park, a police officer said.
The child and another two victims were in critical condition, he added. At least 10 ambulances were sent to the scene, bringing victims to several hospitals.
Many of the victims were shot in arms, legs or feet. A 24-year-old man was shot twice in the abdomen and was in serious condition, spokesman of the Chicago Police Department Ron Gaines said.
"We believe that the motive for the shooting was gang-related," he said. "At this point, detectives are out questioning witnesses trying to find out what happened."
No one in connection with the shooting had been arrested, according to local authorities.
Gun violence has raged in Chicago in recent years, mounting to more than 500 murders in 2012, the FBI said this week in a report.
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