Authorities were urging people to remain calm on Tuesday night after the broadcast of a chilling video that terrified millions. The video, which was broadcast nationally on CNN, appeared to show nine extremists glaring into the camera and making a series of escalating threats. The radicals increasingly violent rhetoric and palpable hatred rattled viewers across the nation, sources said. Experts who viewed the video acknowledged that the words and images contained in it were alarming, but advised the public to remain calm until the extremists threats could be authenticated. At this point, there is no reason to believe that any of these individuals are credible, one expert said. But such assurances did little to soothe viewers like Carol Foyler, of Kansas City, who watched the video in horror. These people are clearly dangerous and must be stopped, she said. Watch: We test which New York City establishments allow in a menagerie of emotional-support animals. 