Kellenberg High School has received three threats in three days, according to an email to parents.

Thursday’s threat was received at around 2 p.m. Students were told to shelter in place at the school. Nassau County police responded to the school and the building was searched. A police spokesperson says the threats were unfounded.

The Kellenberg threats highlight a growing problem on Long Island.

Police were at Stimson Middle School in Huntington Station after threats were made against students.

Police also responded to Bellport Middle School, after a student was reportedly heard saying they had a gun.

The incident at Bellport Middle School was a false alarm.

Police are investigating the threats at Stimson Middle School.