Students and teachers at Scarsdale High School saw extra security on campus Tuesday after a former student posted an apparent threat on Instagram.

The school district says the former student, who is developmentally disabled, posted an Instagram message Monday telling followers not to go to school. A message to the GroupMe messaging app followed, reading "don't go to school today boys," alongside a handgun emoji.

In a letter to parents, the principal downplayed the threat, but community members seemed rattled. Many students stayed home from school for the day.

One senior told News 12 that more than half of her history class was absent.