Montana’s KRTVMichigan’s, WNMU-TV and WBUP-TV were victims of this zombie prank. The channels later said that somebody had hacked into its system. The message warned zombies were attacking the living and warned people not to approach or apprehend these bodies as they are extremely dangerous. Officials with the stations in Michigan said law enforcement authorities determined the attack originated outside the U.S. The message was quickly removed and KRTV broadcast an apology, “Our apologies to those who were scared, shocked or confused”
Source: https://thehackernews.com/2013/02/hacker-broadcasts-zombie-warning-on-tv.html