The false alarm occurred around 9 a.m. on a downloadable app called Yik Yak, an anonymous messaging app that appears to let people complain about other people, places and things, according to the Orange County Sheriff's Department.
Students and teachers were told to shelter in place as a precautionary measure while authorities investigated the threat.
Sheriff's deputies said Thursday afternoon that nothing suspicious was found, and the lockdown was lifted around 1 p.m. Deputies stayed on campus until school ended around 3 p.m.
Authorities are trying to track down the Yik Yak user who created the bomb scare.
