(WASHINGTON) -- Parents, students and school districts around the country were on edge Friday after warnings about threats of violence at schools proliferated on social media.
The warnings about the threats -- which were not specific or deemed credible -- led to increased police presence and some districts closing as a precaution and came in the wake of a school shooting in Michigan that left four students dead.
White House press secretary Jen Psaki called the situation "unacceptable."
"We know a number of schools across the country are closing today, and some parents are keeping their children home," Psaki tweeted.
"Today is another reminder of how many kids and parents live in fear of school shootings or violence. It is unacceptable," she continued. "This Administration has made historic progress on executive actions to reduce gun violence, but there is so much more work to do."
And TikTok, where discussions about rumors of the threats appeared, said it was working with law enforcement, but "have not found evidence of such threats originating or spreading via TikTok."
"We've exhaustively searched for content that promotes violence at schools today, but have still found nothing," the company wrote in a tweet Friday afternoon. "What we find are videos discussing this rumor and warning others to stay safe."
"Local authorities, the FBI, and DHS have confirmed there's no credible threat, so we're working to remove alarmist warnings that violate our misinformation policy," the company added. "If we did find promotion of violence on our platform, we'd remove and report it to law enforcement."
The Department of Homeland Security urged schools to stay vigilant Friday as word of the warnings unfolded.
"DHS is aware of public reporting that suggests possible threats to schools on December 17, 2021," the agency tweeted Friday morning. "DHS does not have any information indicating any specific, credible threats to schools but recommends communities remain alert."
In New York City, the NYPD said Thursday the department was aware of "posts circulating on TikTok concerning a potential school shooting on Friday," but there was "no credible information to suggest this threat is specific to any school in New York City."
The NYPD said it was sending extra resources to NYC schools as a precaution.
Other schools have closed due to the threats. In Wisconsin, the Platteville School District said it canceled school Friday due to a potential threat of violence.
In California, the Los Angeles Unified School District said classes will be in session Friday despite the threats.
"There is no reason to believe our schools are in any danger," the district said Thursday.
Santa Monica police said they'll be highly visible at schools Friday even though there aren't specific threats.
The FBI's Los Angeles field office said, "While we continue to monitor intelligence, we are not aware of any specific threats or known credible threats to schools in the Los Angeles region at this time."
ABC News' Josh Margolin, Molly Nagle, Luke Barr and Ahmad Hemingway contributed to this report.
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