CHICAGO — A Lollapalooza security guard was arrested after being accused of posting fake mass shooting in order to leave work early.

Janya Williams, 18, is facing the charge of calling in a fake terrorism threat, which is a felony, after being taken into custody Friday afternoon in the 700 block of South Columbus Drive.

According to a court document, Williams was accused of sending her Andy Frain Services supervisor, which was the company providing security, a screenshot of a Facebook threat.

Detectives believe Williams made the threat herself under a fake profile named “Ben Scott.” In it, the post read “Massive shooting at Lollapalooza Grant Park 6:00 p.m.,” according to the court document.

The supervisor then contacted her supervisors and the FBI was soon involved. An analyst with the FBI was able to trace the post to back to Williams and had her location, documents allege.

Williams was taken into custody for questioning and told detectives that she created the fake post because she wanted to leave work early, the document said.

Williams had a pending case in a retail theft at the time of her arrest.

Lollapalooza lasted four days from Thursday to Sunday in Grant Park and is coming back following a ten-year extension that was recently announced.