SILVERDALE — A Central Kitsap School District ninth-grade student was arrested Dec. 8 and booked into the juvenile detention center on charges of threats to bomb and possession of an incendiary device.

Sheriff’s patrol deputies responded to Central Kitsap High School shortly after 10 a.m. Dec. 8 concerning information received by school administrators that a student on campus was in possession of some type of explosive device.

The student had been detained by administrators who had found the item in his backpack. The teen, together with his guardians, cooperated with the investigation, the sheriff’s office reported.

The device was described only as a “commercially manufactured explosive device that falls under the jurisdiction of the Bureau of Alcohol, Tobacco, Firearms and Explosives, U.S. Department of Justice,” and requires a federal explosives permit.

Sheriff’s investigators determined that the student brought the device to school after communicating with other students via social media the previous night. “There had been discussion about possibly detonating the explosive, either on campus or off-campus, during the time period when a student assembly was scheduled to take place,” the sheriff’s office reported.

With permission from the student’s guardians, sheriff’s investigators recovered four additional explosive devices from the guardians’ residence.

Detectives are trying to determine how the boy acquired the explosives. The devices were turned over to a sheriff’s sergeant who is an explosive ordnance technician and a member of the Washington State Patrol Regional Bomb Squad. The explosive devices were secured for eventual destruction, the sheriff’s office reported.