[Skullmeat]

This is quite of interesting hack. Clearly the hacker has some knowledge with radio frequencies and how the sirens will react to them. I believe the hacker was some kid he knew about and wanted to see the damage he can do. I'm almost 100% sure that's the case. There's no other reason to flood the 911 pipelines of that area unless he wanted/had some people to do a heist, while this was happening. That would just involve too much time and planning and seems impossible too if he wanted to get away without proof of them even doing the heist. so my conclusion is that , it's some kid with some knowledge of radio signals and how these sirens respond to them, he's definitely not getting caught any time soon, maybe if he tries again but i doubt it,

That would be my guess. Chances are the culprit was also unlicensed as well. Licensed operators have spent far too much time to get their equipment and FCC licenses, to abuse the system and loose them.