Greg MacDonald, chief executive officer of the Montana Broadcasters Association, said the Emergency Alert System warning of "dead bodies rising from the grave and attacking the living" on two Great Falls TV stations Monday evening was duplicated on stations in Michigan, California, Utah and New Mexico, the Great Falls Tribune reported Wednesday.
MacDonald said FBI and Federal Communications Commission investigators believe the hacking originated from outside the country.
"It's a serious issue. Initially people laughed about zombies, but then you start digging and find that it's not that funny," MacDonald said.
2014: The Year in Music [PHOTOS]