Authorities lent no credibility to a second warning appearing Monday night on social media that a shooting would occur at Brunswick High School, although enrollment was down and police presence was up on the campus Tuesday at 3885 Altama Ave.

The posting followed the arrest Monday afternoon of a 16-year-old who allegedly used a social media app to warn students that he planned to commit a shooting on campus. The threat greatly disrupted the school day, prompting a traffic jam on Altama Avenue as a horde of parents descended on the campus to pick up students. The threat prompted local and federal law enforcement officers to join Glynn County Schools police at the campus, where the boy who allegedly made the threat was arrested around 2:30 p.m.

He is currently being held at the state Youth Detention Center in Savannah, county police said.

A second warning appearing Monday night on Snapchat and Facebook warned that the boy police arrested was set up as a distraction to a shooting incident planned for Tuesday. Police and school officials concluded that this post’s threat was not valid.

“Through the joint investigations with our school resource officers, school administrators and law enforcement partners, our results revealed there is no real legitimacy to those claims,” BHS Principal Scott Spence said in an automated phone message to parents. Additional County Schools Police officers were stationed on campus Tuesday, as were officers from local police departments.

About 36 percent of the school’s nearly 1,800 students were absent from school Tuesday, a county schools spokeswoman said.

Meanwhile, the initial threat had reverberating consequences Monday that affected schools from Massachusetts to Canada, according to reports. Monday’s threat identified Brunswick High by its initials, BHS. The threat first appeared to numerous to BHS students around noon on the Apple app “AirDrop.” But it was picked up and reposted on Snapchat, misinterpreted by students in Brockton, Mass., as a threat against Brockton High School. It also was misinterpreted as a threat against Bowmanville High School in Ontario, Canada.

In both instances, local authorities determined the true source of the threat and notified parents accordingly.

“We want to advise Bowmanville High School students/parents that the threat was directed to a school in USA in Georgia,” the Bowmanville Regional Police said in a tweet. “An arrest was made by Glynn County Police.”

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