Shamus Patton, 18, pleaded guilty to charges of battery, aggravated battery and criminal gang activity, The Indianapolis Star reported Thursday.
Marion Superior Court Judge Carol Orbison, in sentencing Patton to eight years in prison, two years in community corrections programs and two years on probation, called the shootings "absolutely horrendous."
In the shootings, thought to be gang-related, Patton fired into crowds at two Expo activity sites in downtown Indianapolis on July 17, 2010, wounding nine victims ages 10 to 19.
The Rev. Charles Harrison, head of a group of ministers attempting to improve relations between police and black youths, said the shootings made people realize that gang violence in the city's neighborhoods could also threaten the city's downtown area.
"I think we have to be vigilant and report what we see," Harrison said. "I think we can no longer be quiet about what's going on."
Patton's sentence should be an example, he said.
"I think we have to send a strong message to our young people in the community," he said, "that this kind of behavior is not going to be tolerated."