New Jersey cable customers were unnerved after a false alert went out on their televisions warning of an unspecified emergency.
Optimum cable customers in Morris County saw a blue screen with background jazz music that warned of an emergency.
NJ.com reports Altice USA, Optimum's parent company, said Thursday the message was sent in error while they were conducting an emergency alert system test.
Scott DiGiralomo, director of the county's Law and Public Safety Department, says a true emergency alert would specify the nature of the emergency and how to react.
He says New Jersey State Police and the county Office of Emergency Management are investigating where the alert came from. Altice says its teams are working to ensure this doesn't happen again.
In May 2017, some New Jersey residents got a false alert about a nuclear power plant emergency.