Educators announced plans to increase security in response to TikTok posts warning of shooting and bomb threats at schools around the country Friday as officials assured parents the viral posts were not considered credible. The social media threats had many educators on edge as they circulated in the aftermath of a deadly school shooting in Michigan, which has been followed by numerous copycat threats to schools elsewhere. School officials in states including Arizona, Connecticut, Illinois, Montana, New York and Pennsylvania said Thursday there would be an increased police presence because of the threats. The vague, anonymous posts circulating online warned...