(KRON) — A disturbing note threatening to “shoot up” a classroom at Palo Alto High School was found by a teacher on a classroom door Tuesday morning, police said. Instead of taking a scheduled final exam, students were ordered to shelter-in-place.

At 8:57 a.m., 911 dispatchers received a call from administrators at Palo Alto High School at 50 Embarcadero Road reporting the note.

“A teacher had arrived at school that morning and discovered a written threat of violence taped to the front door of the classroom. The threat indicated that the person who left the note intended to ‘shoot up’ the classroom later that morning,” the Palo Alto Police Department wrote.

A final exam was scheduled to occur later that morning in that same classroom, police said.

Police worked in collaboration with school administrators, who opted to place the
campus into a shelter-in-place status as a precaution while the investigation unfolded.

School officials lifted the shelter-in-place around 10:30 a.m. and no arrest was made. Officers are still actively investigating the incident. “It is possible that once a suspect is identified, that person could face criminal charges,” PAPD wrote.

Police officers will be on or near the campus for the remainder of the school day to help
students and staff feel safe and secure.

PAPD wrote, “As always, police encourage anyone who has information about a possible threat to immediately contact our 24-hour dispatch center at 650-329-2413. Anonymous tips can
be e-mailed to paloalto@tipnow.org or sent via text message or voice mail to 650-383-