ST. PETERSBURG — They started in South Carolina. Their presence shut down schools in Ohio, and prompted law enforcement alerts last week in Pasco County and Largo. Now they're said to be St. Petersburg.

Police are monitoring rumors about violent threats from clowns at Northeast High and other middle and high schools after a picture of a clown peeking out behind a tree was circulated on social media.

School district spokeswoman Lisa Wolf said officials have confirmed that the photo has been altered, however the clown craze has spread to other schools in the district.

St. Petersburg Police spokesman Rick Shaw said police have received five calls about clowns relating to Northeast, St. Petersburg High, Meadowlawn Middle and a Gibbs High student over the past two days.

Three of those calls specifically mentioned a clown's intent to "shoot up" a school. The parent of a St. Petersburg High student told police that the student received a screenshot showing a Facebook message between a student and "Jeffrey the Clown."

"I have an AK47. I'm going to shoot up the school," the message read. When asked which school, the clown said, "I don't know, some random a-- school."

Police received another call in reference to St. Petersburg High one hour later about several text message screenshots that said Jimmy the clown would "come to school and shoot up the school."

A school resource officer this morning investigated several posts on social media regarding St. Petersburg High and Northeast High and believes a former student who recently moved out of state is posing as a clown.

During school Monday, a school resource officer said a student told him that he was messaged by a clown named Bill Barnes, who told the student to look out because he would shoot up the school. There was no mention of school names or student names. One police officer was sent to the school and found nothing.

No arrests have been made, and no threats have been deemed credible, Shaw said. There have been no documented sightings within St. Petersburg city limits.

"So far we've had nothing credible as far as any clown sightings here in St. Pete or St. Pete schools," he said. "Other than people are just perpetuating the problem by claiming clowns are going to do this or clowns are going to do that."

Pinellas County school district spokeswoman Lisa Wolf said officials also were aware of rumored threats toward Seminole and Clearwater high schools, Clearwater Intermediate and Clearwater Fundamental Middle but also determined the threats were not credible.

"They're all over the place," Wolf said.

She added: "But (officials) are of course looking into each rumor, each sighting, each experience to make sure our students are safe."

Last week, a Largo High student told police she was chased from her school bus stop by a man in a clown mask. Wolf said the school did increase patrols, but did not see anything.

And this morning, Pasco County Sheriff's deputies were investigating a clown's threat of violence toward Seven Springs Middle in New Port Richey. Deputies have determined that a student made the threatening post.

The clown phenomenon is part of a nationwide trend in which many people have reported clowns chasing or attacking them, standing outside their homes and making threats on social media.

Contact Colleen Wright at cwright@tampabay.com or (727) 893-8643. Follow @Colleen_Wright.