LOS ALAMITOS (CBSLA) – A suspicious backpack which forced the evacuation of Los Alamitos High School Thursday morning was deemed harmless.

At around 8:30 a.m., Los Alamitos police were informed about an “unclaimed backpack” which was found in an office at the school, according to the Los Alamitos Unified School District.

All students and staff were evacuated to an athletic field and an Orange County Sheriff’s Department bomb squad was called to the scene.

Just after 10 a.m., the bomb squad determined that the backpack was harmless, police said. All students were allowed to return to class.

The exact contents of the backpack were not confirmed.