Coming from a Florida Resident and someone who was pretty much raised in South Florida:
While this is SCARY as fuck to many, I can see how it makes sense in some capacity down here in Florida. MANY people here in Florida carry guns and live their day-to-day lives with guns. Florida is more than just South Beach. In fact majority of Florida is still very "red-neck". People start learning how to use and carry guns as young as 10, depending on where you live.
So for most of us this is shocking, but in Florida this is not surprising. I am not a fan of ANY GUNS period and think they ALL should be banned but I can't say I'm surprised by this. If this was NY or CA, I would be surprised. But not here in Florida. Guns are a normal part of life.