Question for Phoenix Area Residents

My sister called a few minutes ago from a Phoenix suburb and told me that since this morning, there have been 9 airings of the emergency broadcast signal on the local tv stations. She called her favorite of the local stations to ask what was going on. They told her that hers was around the 40th call with the same question. Nobody has an answer as of yet, but my sister is a tad spooked about this.

Anybody have any insight? Anybody with inside information? We've speculated that it is a glitch or that somebody hacked the system and is playing games, but would really like to know that for a fact.

Thanks for any help.