I'm not against the extra security and police, though it's unfortunate since I'm sure it's both a significant expense for the park and another thing the local police probably didn't plan on having to deal with.
But the bag policies and chaperones? Like Amy said earlier, either someone got a weapon through the scanners that already existed or (more likely if even a few of the people who were claiming to have been there on social media actually were) got it through or over the fence. I don't see how banning bags helps if someone can just bypass security entirely like that. Even single bag they see gets checked anyway, so no one is sneaking a weapon in inside one unless they're somehow sneaking the entire bag in anyway. It's just a pain for the 50% of the population whose clothing designers haven't heard of pockets. I'm usually the "group mom" when I do parks with friends and try to remember to bring along things like advil, dramamine, extra sunscreen etc etc to make sure no one's day ends up miserable. It's much nicer when I have a place to put things like that.
As far as chaperones..I'm pretty fine with that just to stop the petty trouble kids get up to, but for preventing shootings, how many serious incidents are really caused by people under 17, who don't know anyone over 21 to get them in?
I don't know how the park should handle it, since this is a problem going far outside of any one park now, I just don't like seeing them making a big deal about how they're going to make it safer with policies that realistically aren't.