San Ysidro High School received another threat – the eighth such one in two weeks – on Friday morning.
San Diego police said the school was temporarily placed into lockdown after they were notified just before 8 a.m. of the threat.
Officers swept the school’s campus and found nothing suspicious.
Officers said the school received a voicemail early Friday morning threatening a bomb and a possible gunman on campus.
The last two threats occurred two days ago -- also morning phone-in threats.
Friday morning, San Ysidro Principal Hector Espinoza issued a statement, saying the school, the school district and San Diego police are treating the threats very seriously.
"Although all threats to date have been 'low-level status,' rest assured we take them seriously and take all precautions necessary to protect our students, staff and community," the statement read.