Two Hilo High School students suspected of setting off a small explosive device at the school on Thursday have each been suspended for six days, the Department of Education reported.

Donalyn Dela Cruz, DOE spokeswoman, said the teens were suspended by the school for disorderly conduct and insubordination because they left a classroom during a lockdown without authorization.

Big Island police opened a terroristic threatening investigation and arrested two 16-year-old boys.

Further DOE disciplinary action will depend on the police investigation, Dela Cruz said.

Because the teens are minors the matter will probably be handled by the Family Court behind closed doors.

Hilo High School went into lockdown shortly after 11:30 a.m. Thursday after a small explosive device detonated in an open corridor outside the school’s auditorium, Dela Cruz said.

No one was around when the explosion occurred. No one was injured.

Police responding to the scene found the remnants of a plastic container and an unidentified liquid substance.

The lockdown was lifted at the school at about 1 p.m.