Why?
I mean what's wrong with people wanting to take in the gravity of the situation for themselves?
I don't want victims to feel gawked at or for people to get in the way of anything important, but as long as people are respectful I think it's probably a good thing that people see the seriousness for themselves.
It's our country. This is hitting some people a million times worse than others, but we're all impacted in some way.
I think it would be more productive to say, "If you're going to visit: Don't get in the way. Be respectful. Stay safe. And bring whatever you can to help the affected people" - perhaps with a list of what is needed.