JOLIET, Ill. – Four Illinois teens are facing child pornography charges after they allegedly filmed themselves in a group sex scene and posted the video online.

The Joliet Central High School students – three males ages 14, 15, and 16, and one female, 15 – were arrested on child pornography charges Friday after the girl’s mother saw the video and called police, ABC 7 reports.

Joliet Police then identified the students in the video.

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“The child pornography offense that was charged is in place for a reason, because we don’t want to accept that type of behavior as a society,” Joliet Police Chief Brian Benton told the news site.

“So I think it’s making a strong statement and I think it’s important to do so to send the message to others: that kids shouldn’t be involved in this type of behavior and hopefully this will serve as a deterrent,” he said.

Benton told the media all four of the students were willing participants in the sex, but distributing the video online is considered child pornography. Joliet Deputy Chief Al Roechner told The Times Weekly the students posted the video to Twitter, a Class X felony in Illinois.

The video was removed within a day of when it was posted, he said.

The teens were charged as juveniles when they appeared in court Monday, and are currently held at the River Valley Justice Center.

“Regardless of whether or not the participants are willing, because they are under age it’s a criminal offense for them to share or upload videos, texts, or images of themselves in a sexual act like this,” Benton told NBC Chicago.

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Many students and parents were surprised to learn about the charges.

“It’s horrible, I’m shocked,” a parent told NBC Chicago.

“I think it’s horrible, but I think it’s like, why even put it out on social media just to get attention,” student Maritza Ochoa said.

“They were not getting enough attention from their friends or something, and they just wanted to be cool,” student Analyn Gomez said. “I heard they were freshmen, so that makes like, us look bad.”

Parent Patty Arias believes parents should do more to control how their kids behave.

“It’s out of control, and I think that boundaries are not respected whatsoever,” she said. “I think parents really need to stay on top of their kids.”

Benton agreed.

“I am a parent, a concerned parent, and this is very scary,” he told NBC Chicago. “Decisions like this can stay with them the rest of their lives.”

School officials did not respond to media calls for comment. NBC Chicago reports that anyone who copied the teen sex video online and reposts any portion of it will also face criminal charges.