The Montana Television Network says hackers broke into the Emergency Alert System of Great Falls affiliate KRTV and its CW station Monday.
KRTV says on its website the hackers broadcast that "dead bodies are rising from their graves" in several Montana counties.
The alert claimed the bodies were "attacking the living" and warned people not to "approach or apprehend these bodies as they are extremely dangerous."
The network says there is no emergency and its engineers are investigating.
A call to KRTV was referred to a Montana Television Network executive in Bozeman. Jon Saunders didn't immediately return a call for comment.
The Great Falls Tribune reports the hoax alert generated at least four calls to police to see if it was true.