ALISO VIEJO (CBSLA.com) — St. Mary of All Angels, a school in Aliso Viejo, was on the receiving end of an emailed-in threat Monday.

Authorities were immediately contacted by school officials and arrived on campus to begin conducting a thorough investigation.

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The school reportedly held all activities inside as the investigation proceeded Monday.

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Sheriff’s deputies assessed that the campus was secure, and school security personnel were in cooperation with authorities.

It was not immediately clear whether the threat was valid or whether the school will cancel classes throughout the week.

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The details of the threat were not immediately released.