It’s a video that's extremely disturbing to watch. A group of teenagers, beating up a special needs 15-year-old girl.

Superintendent Eddie Johnson says the alleged attackers, who aregirls 13, 14, and two 15-year-olds were the victim's friends.

We won't know their names because they're minors; all four teens were charged with aggravated battery.

Officials say three of the four turned themselves into police with their parents Wednesday night. The fourth girl was arrested Thursday afternoon.

The video, which was posted on Twitter, shows the victim was surrounded by five girls and a teenage boy before she's repeatedly punched.

Prior to the beating, the victim was reported missing for nearly a week when the video was shared online.

Chicago Police believe the group of girls beat her up after she refused to carry out a sex act on a guy.

The victim, according to her family, is recovering but she is in the care of the Illinois Department of Child and Family Services while the investigation continues.