A bomb threat Wednesday afternoon forced the evacuation of Monroe-Woodbury High School in Central Valley.

School officials enacted emergency procedures just before lunchtime after a note was discovered in a boys bathroom. About 2,500 students evacuated the building and were later sent to the nearby middle school.

At least 10 K-9 units were called in to investigate the threat.

It took local police, along with state troopers, almost three hours to thoroughly search the building. No explosives were found.

Police eventually gave the all clear just before the normal dismissal time, and students were sent home at their usual time.