Chicago police say that four teenage girls turned themselves in after a massive outrage over a video of a brutal beating they gave to a special needs 15-year-old girl who went missing after the attack.
Police characterized the charges as "sick and disgusting crimes."
The video went viral on social media after the attack on Sunday. It shows more than three people suddenly strike and beat a girl who appeared to walk with them as if they were friends.
The girls who turned themselves in to the police are ages 13, 14, and two are 15. Three are charged with aggravated battery while the third is charged with mob action.
Police say that the girls are also volunteering information about the other persons involved in the attack, and the investigation is not over.
"It broke my heart to see this group of young people turn on her and escalate it into what we saw, a physical assault," said Police Superintendent Eddie Johnson. "There simply cannot be room for this type of divisive and hateful behavior."
There are reports that she was attacked because she refused to participate in a sex act being planned by the assailants, who believed she was going to call the police.
Johnson would not confirm the report, but offered a cryptic comment about the claim.
"There was some things going on that these young ladies wanted her to do that she didn't do," he said, "but we'll leave it at that for now."
The girl went missing after the attack but was found on Tuesday on a bus by a friend.
Here's a local news report about the attack:
Disturbing Video Shows Teens Attacking Girl On South Side www.youtube.com