A 20-year-old off-campus student has been jailed on charges that he posted a social media threat to shoot people at a popular gathering area on Penn State's main campus.



Jong Seong Shim, of Tinton Falls, New Jersey, told police on the campus about 140 miles east of Pittsburgh that his post on the social media site Yik Yak was a "prank," according to a criminal complaint filed Monday by campus police.



But Police Chief Tyrone Parham said in a statement that, "Alarming an entire community is not considered a joke."



The sophomore engineering student was jailed after he was unable to immediately post $100,000 bond following his arraignment on two counts of making terroristic threats and one count of disorderly conduct. He faces a preliminary hearing Oct. 22 before a district judge at the Centre County Courthouse in Bellefonte, according to online court records, which do not list a defense attorney for him.



The message was posted about 10:30 p.m. Saturday threatening to shoot people at the HUB, a center of campus social life that includes various eateries and other places students meet to socialize. Several students alerted campus police when they saw the post.



Yik Yak is a social media service that enables users to post anonymous comments that are deleted a short time later, and visible only to those within 1.5 miles of the poster, university police said.



Police took the threat seriously since it targeted the HUD, where there likely would be large numbers of people. Police had planned to have additional officers on patrol before they were able to trace the post to a mobile device used by Shim.



"I am going to kill everyone in penn state main on Monday. I got 5 bet mags of ar 15 and shoot everyone in the hub at 12:00," the post said, referring to ammunition and a type of rifle known as an AR-15. "This is a warning."



Police said they worked with Yik Yak officials to identify the mobile device used to post the message as well as Shim's location when that occurred.



There were no weapons, or any other indication that Shim planned to carry out the threat, in his off-campus apartment, police said.



"We are grateful to our very alert and diligent students who first discovered this threat and raised their concerns with police," Steve Shelow, Penn State's assistant vice president for Police and Public Safety said in a statement. "It is quick reporting by observers and strong cooperation among law enforcement agencies that allowed us to move swiftly to identify and apprehend the suspect."



University officials didn't immediately comment on Shim's status as a student.