Moorpark High School was on lockdown but there was no imminent danger, school officials said.
The threat was triggered by a threatening voicemail left on a school answering machine, according to Ventura County Sheriff's Department spokesman. Someone had made a general threat referencing the school.
The school went into lockdown at 8 a.m., with students staying in their classrooms, according to Capt. John Reilly.
A tweet from the school's account said the lockdown was a precautionary measure as administrators search for a student.
MHS is currently in lockdown. This lockdown is a precautionary measure. We are attempting to locate a student. There is no imminent danger. — Moorpark High School (@MoorparkHighSch) April 27, 2015
The lockdown was lifted at around noon, according to a Sheriff's Dept. news release. The investigation was concluded, but further details were not available.