I don't believe that. Shutting down a few remote towers is fairly simple but shutting down a nationwide grid that handles millions of calls every minute is about as difficult as shutting down the internet. You'd need all the carriers to agree to shut down. Too difficult.
You know, maybe they wanted all cell phones shut down in case there was a chance any bombs would be set off by cell phone. They could call in an explosion. The LE is being extra cautious.
I think this is terrorism and the cops know it but they don't want to scare us. Guess what? We're already scared but I'm going to tough it out. Of course, I'm not up there but we all feel this. Every time.