The teenager, who was arrested Tuesday, made the threats on Yik Yak, a social media app, according to Detective Lt. William Sullivan.
Making terrorist threats is a felony. The teenager was released to the custody of his parents after being arraigned in Ossining court. He was charged as an adult but if eligible for youth offender status.
Sullivan said the investigation involved using the joint terrorist task force, which involved the FBI, New York State Police.
"It was a prank call, but this is still a serious situation," Sullivan said. "The FBI was involved. It was frightening for the people in the school. People don't realize that what you post on social media can have serious consequences."
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