A Long Island teenager was arrested after posting threats on social media concerning a shooting and bombing at his Mount Sinai school today.

The posting was made on the social media site Yik Yak, in which users can write posts anonymously—although not, apparently, so anonymously that the 15-year-old student wasn't promptly tracked down by authorities and charged with making a terroristic threat. Several parents took note of the posting and alerted the school, which in turn notified police.

The teen has been charged as a juvenile and will appear in Family Court today, Newsday reports.

Police are also investigating a second incident involving similar threats at a school in West Islip.