Updated 2:55 p.m: Students have been released from campus and the lock-down has been lifted, according to a message sent out by the Police Department.
The bomb threat came from an email sent to the school that had to with a teacher being fired, according to officers at the scene.
Updated 2:38 p.m: The lockdown is still in place, though the Arcadia Police Department is trying to figure out the best way to release kids to their parents, according to Travis Walton, a spokesman for the department.
The investigation into the threat is still ongoing, he added.
Parents have gathered outside the school and are waiting for their kids to come out.
Update, 2:10 p.m.: Authorities are aiming for a regular dismissal time for the students as police continue to to search and clear buildings around the school. The lockdown is still in place.
Update, 1:40 p.m.: Authorities are checking and clearing numerous areas of the school for anything that might look unusual in light of the bomb threat, according to scanner reports.
Update: Parents have been notified about the lockdown, which was instituted around 12 p.m, according to school official Marilyn Daleo.
Security guards are not letting visitors on campus as of 1:20 p.m.
The Arcadia Police Department is currently investigating an unspecified bomb threat on the campus of the Arcadia High School, 180 Campus Dr, according to information provided by
The Arcadia Unified School District has placed the campus on lockdown and students have sheltered in place at the direction of AUSD while the campus is searched. Further information will follow when it becomes available.
Parents should not respond to AHS at this time and will be notified as to dismissal procedures.
Police and fire personnel are on scene and are coordinating efforts with AUSD personnel.
Campus Drive has been closed to through traffic between Santa Anita Avenue and Park Avenue.
This story will continue to be updated as information becomes available.