A series of threatening messages over anonymous social media app Yik Yak resulted in Manhattan Beach’s Costa High School decision to close for two days as authorities investigated the threats.

The first message was posted on Monday and read, “If you go to Costa, you should watch out very closely at school today,” according to the Los Angeles Times. A student notified a teacher about the vague message, which prompted authorities and local officials to search the school. They did not find any additional evidence to support the message’s contents.

A second message was reportedly sent later that afternoon which read “nice try Costa, today was just a drill,” which was followed by a third message around 8 pm stating “tomorrow at 2 be ready Costa, you’re going on lockdown,” notes the Times

A report by the local CBS News affiliate in Los Angeles noted that a total of five message were sent and that one of them, also sent on Monday night, read: “Almost every school shooter left a warning before committing the crime and everyone ignored them, just remember.”

That prompted school officials to notify parents and students that they would be closing the high school on Tuesday. The closure carried into Wednesday as authorities searched for a source for the threats.

Classes resumed on Thursday and a message from the district stated, “We look forward to welcoming all students back to campus, but understand that parents/guardians have the right to make an informed decision for their child.”

The app has reportedly disabled its ability to operate at Mira Costa High School through the use of geo-fencing security software, which a CBS News reporter was able to verify while covering the story there.

The threat follows several other threats that have been sent through the anonymous Yik Yak app including this past week at an Illinois High School and a bomb threat in March of this year at San Clemente High School, notes the Times

Two weeks ago, a bomb threat at Centennial High School in Compton resulted in an hour-long evacuation of the school until authorities determined it was safe for faculty and students to return.

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