Among the 12, one is a three-year-old, who was shot in the incident and four are said to be in critical condition. Reports said that the 11 people were transported to the hospital by emergency services that reached the spot.
The incident comes days after 12 people were shot dead during a shooting spree at a Washington naval base.
No suspects have been taken into custody as of now in the park shooting spree.
Chicago has been witnessing a lot of shooting incidents this year that has claimed many lives. According to FBI's annual crime report, Chicago had 500 homicide cases in 2012 as compared to 431 in 2011 and this was the largest in any American city.