Authorities believe the threats aren’t credible, but schools are still urging caution.

Today, public school districts around the United States issued an advisory to students and parents about a supposed threat of shootings and bombings circulated through social media platform TikTok. Apparently, as part of a new TikTok “challenge,” anonymous users have been posting generic threats of violence and directing them toward public schools in multiple states. School districts have respondedly differently to the threat; some, such as those in Montana and New York, have opted for an increased police presence around the school’s vicinity, while others, such as schools in California and Texas, opted to close schools entirely for the day.

“We are writing to inform you and not alarm you,” school administrators in Oak Park and River Forest, Illinois, said in message to parents. “We have been made aware of a nationwide viral TikTok trend about ‘school shooting and bomb threats for every school in the USA even elementary’ on Friday, December 17.”

The precise origin of the threats or the “challenge” that inspired them is not known. As the threats are all extremely generic in nature, law enforcement officials do not believe them to be credible. Even so, they are taking the investigation into the matter seriously.

School districts increase security due to TikTok videos warning of school shootings and bomb threats despite assurances the posts aren't deemed credible https://t.co/MR80Vd3kdu

— CBS News (@CBSNews) December 17, 2021

In a statement to CBS, a representative of the FBI said that the bureau “takes all potential threats seriously. We regularly work with our law enforcement partners to determine the credibility of any threats. As always, we would like to remind members of the public that if they observe anything suspicious to report it to law enforcement immediately.”

TikTok, for their part, have promised to cooperate with the investigation as required of them. “We handle even rumored threats with utmost seriousness,” the platform said in a statement, “which is why we’re working with law enforcement to look into warnings about potential violence at schools even though we have not found evidence of such threats originating or spreading via TikTok.”