TikTok, owned by ByteDance Ltd, is among several social media companies that have faced criticism for spreading harmful videos, particularly among kids ​​

New York, December 19 (RHC)-- A wave of school-shooting threats circulating on TikTok and other social media prompted some U.S. schools to close Friday and others to bolster their police presence.

Generally, the threats don’t name specific schools and local and federal authorities have said many lack credibility.  Still, the threats are taken seriously, leading schools in Michigan, Washington and elsewhere to temporarily keep kids home.  Many videos show a text warning of a bombing or shooting on Friday, without schools, districts or even states listed.

There have been nine school shootings and 235 so-called nonactive shooter incidents this year, according to the Center for Homeland Defense and Security, and districts and law enforcement say they take each warning seriously.

New Jersey Governor Phil Murphy said that while there are “no known specific threats,” he has spoken about the viral posts with the state’s attorney general and security officials.  “We will work closely with law enforcement to monitor the situation and remain prepared,” Murphy said on Twitter.

Oxford Community Schools in Michigan, where a boy killed four students in late November, closed all buildings due to a new shooting threat.  Seattle police opened investigations into two schools and closed another after staff alerted authorities to social-media posts, according to a press release.

Schools in the New York City metro area have also been affected. Pelham Public Schools, in Westchester County, New York, shifted classes online Friday after a threat against the high school on Snapchat.

In Glenview, Illinois, a Chicago suburb, police deemed shooting and bomb threats circulating on social media not credible, according to a news release on the department’s Facebook page.