Breaking news update, 12:55 p.m. Monday: Philadelphia police say they have identified a 13-year-old girl who participated in the posting of the social media threats.

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Several apparent threats against a number of Philadelphia schools were made on Instagram Saturday, all coming from accounts that seem to associate with the recent wave of people dressing and posing on social media as clowns in an apparent attempt to frighten and harass.

The threats list specific schools, and one post specifically threatens to "blow up" the Philadelphia School District headquarters at 440 N. Broad St.

The school district and the Philadelphia Police Department issued a joint statement on Sunday afternoon in response to the "scary" threats.

“The School District of Philadelphia's Office of School Safety alerted both the Philadelphia Police Department and the Office of Homeland Security Saturday upon learning of these disturbing social media posts," the statement said. "The safety of our children and the communities surrounding our schools is a top priority for us and we are taking this matter seriously.”

Police are actively investigating the threats and trying to find out who is responsible for them, while the district's Office of School Safety is working with police to ensure students' safety when schools reopen Wednesday after a holiday break.

The accounts all use the word "clown" in their names and feature pictures of clowns in their bios. Several listed city schools along with dates on Saturday night.