Law enforcement agencies responded to several Southern California schools Tuesday after they received what were later determined to be false claims of violence at the campuses.
The hoax reports were received at roughly the same time Tuesday morning, drawing officers and deputies to the campuses.
In Rancho Cucamonga, police said they were aware of a threat made at Alta Loma High School and Alta Loma Junior High School.
"It was determined to be a hoax," police tweeted. "There is no active shooter nor any threat to students or staff."
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Authorities also responded following a similar claim involving the California School of the Arts in Duarte. After a sweep of the school, authorities determined there was no threat.
The Los Angeles Sheriff's Department said it is investigating to determine the source of the call. It wasn't immediately clear whether the calls were placed to emergency services or the schools.
The Ontario-Montclair School District said it was among several locations nationwide that received hoax phone calls.
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"Out of an abundance of caution and at the direction of Ontario Police Department, some of our OMSD schools were briefly placed on a precautionary lockdown," the school district tweeted. "As you know we take all matters of this nature with our utmost urgency."
Ontario police said the false shooter reports appear to be swatting calls -- false reports intended to draw a large law enforcement response to a home, business or school. The department said it also responded to a false report at Chaffey High School
"We rapidly responded to the school and determined there was no credible threat," the department tweeted. "Swatting calls put undue strain on police resources, schools, and students."
NBCLA has reached out to the school districts and law enforcement agencies for more details.
