By CBSLA Staff

VENTURA (CBSLA) — Four students in Ventura and Oxnard faces charges Monday of making criminal threats of violence to a school campus.

Police have been investigating social media posts threatening Ventura County schools since last week. Most of the threats have been deemed not credible, but at least four students have been arrested in connection with the posts.

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A concerned parent called Ventura police to report a student at Balboa Middle School who has recently been talking about being involved in a school threat, Ventura police said Monday. Detectives looking into the threat arrested the student at his home on suspicion of criminal threats to a school.

The Sunday night arrest follows three more made in the wake of separate threats against Pacifica High School and Oxnard High School. Two 16-year-old students admitted to being behind a social media post threatening a lunchtime shooting at Pacifica High School as a joke, according to Oxnard police.

(credit: CBS)

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In a separate incident, a 14-year-old student was arrested after posting a threat on social media against Oxnard High School. The threat was deemed not credible, and police identified and arrested the student by the end of the school day. The student admitted to officers there was never a real threat to the school, police said.

These three students face charges of making criminal threats to a school.

The disturbing rise in school shooting threats made on social media prompted a rebuke from Dr. Cesar Morales, the superintendent of Ventura County schools.

“Students need to understand that posting threatening and harassing material to social media is no joke,” he said in a statement.

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In just one week, a student at Redlands High School was arrested for having an unloaded “ghost gun” on campus, a seventh-grade student at Joe Baca Middle School in Bloomington had to be investigated after being rumored to make a threat against the campus, and a threatening post made on Snapchat ended with the removal of a student at Santa Monica High School. A student at an unidentified school in Buena Park was taken into custody due to a social media post that appeared to be “threatening one of our schools,” according to Buena Park police, and in-person classes were moved canceled at Cantwell-Sacred Heart of Mary High School due to another unsubstantiated threat.