Girl Suspected Behind At Least 1 Social Media Threat Against Mira Costa High School

MANHATTAN BEACH (CBSLA.com) — Authorities say they've identified at least one person they believe was behind at least one post on the social media app Yik Yak that prompted the two-day closure of a South Bay high school.

Manhattan Beach police said Wednesday that they've interviewed a female juvenile in connection with the threatening social media posts related to Mira Costa High School.

The unidentified girl was not in custody, and according to police, was not a student within the Manhattan Beach Unified School District.

Officer Stephanie Martin of the Manhattan Beach Police Department described the girl as a South Bay resident who lives with her parents.

"Mom and dad are aware. Mom and dad are cooperating. She's not going anywhere," Martin said. "So looking at all those things and the fact that we're still investigating is the reason why she's not in custody at this time."

Police said their investigation was ongoing, and planned to continue to determine whether others were involved.

A total of five threatening messages, posted anonymously within a 24-hour period, prompted the two-day closure of the school.

The first threat was reported Monday morning by an unidentified student and stated: "If you go to Costa you should watch out very closely at school today."

That post prompted students to shelter-in-place at the school.

Later that evening, three additional threats were posted on the app, prompting the cancellation of classes and all school activities Tuesday.

Police said the messages included the following:

"Nice try Costa. Today was just a drill."

"Almost every school shooter left a warning before committing the crime and everyone ignored them, just remember."

"Tomorrow at 2. be ready Costa. You're going on lockdown."

A fifth and final threat, which stated "If you go to Costa you should watch out very closely on Wednesday," was posted at 10 a.m. Tuesday, officials said.

The posts prompted officials to keep the school closed to students Wednesday.

The school was expected to reopen Thursday with an increased police presence.

No further information was provided.

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