PLAINFIELD, Ind. – Plainfield High School officials implemented increased security measures for students returning from winter break Monday amid a series of online threats against the school in recent weeks.

District officials canceled classes at all schools the day before winter break because of rambling, violent and graphic threats against the high school and a specific student. Ironically, the threats also caused a brief lockdown at a Plainfield High School in a different state after they were reposted locally.

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The anonymous Facebook account has also caused panic by threatening violence at Plainfield, Indiana shops and movie theaters, which were evacuated Dec. 18, the Indianapolis Star reports.

At one point, the Facebook count was deactivated, but resurfaced as students prepared to head back to class last week. A new message posted Sunday threatened to turn Plainfield High School into a “graveyard,” prompting school officials to increase security this week.

School officials issued a statement Sunday informing students and parents that classes will resume as planned Monday, though there’s now a ban on backpacks “until further notice” and other security measures in place to protect students, WRTV reports.

Police searched students’ purses and made them empty their pockets as they were scanned with wands heading into the building Monday.

“It’s nerve-wracking, but I know police are going to do the job well,” senior Sara Laswell told the Star.

“I’m a little nervous,” freshman Rachael Snider said. “It’s also weird.”

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Plainfield police Capt. Jill Lees said there were no issues when officers scanned students Monday. Authorities do not believe the threats are credible, Lees said, though she did not explain why.

“I know a lot of parents are seeking out more information,” Lees told WRTV. “We just don’t have a lot of that at this time. Because they’re still actively investigating this and we don’t have a suspect in custody or a genuine direction for where this is going. We would really hope parents would speak to their children about the safety measures.”

Parents like Kristen Tackett, meanwhile, are crossing their fingers that police know what they’re doing, and sending their kids to school despite the continued threats.

“I’ll never forgive myself if something happens,” Tackett said.

Other parents are less trusting.

“I cannot believe the Plainfield police have not caught this sick person. In case they haven’t noticed, our kids lives are being threatened,” Rich Walker posted online. “I have zero faith in the police right now, I think we need to change the entire bunch. I for one will not be letting my kid go to school on Monday and I have no confidence my child will be safe.”

In the days leading up to winter break, officials in Plainfield, Connecticut put Plainfield High School and Shepard Hill Elementary School on lockdown after the threats against the Plainfield, Indiana school surfaced online and a local reposted the message, NBC Connecticut reports.

The lockdowns were lifted after a couple hours when local police, working with the FBI, realized the mix-up.

Indiana’s Plainfield Community School Corporation closed all schools for the Friday before winter break because of the Facebook threats, as did nearby Danville schools, which received similar threats believed to be connected to the Plainfield threats, Fox 59 reports.

Other area school districts – Franklin Community Schools and Martinsville Schools – also instituted lockdowns before the winter break because of threats of violence.