If gun violence is a disease, then the etiology has to be understood and then the proper diagnosis arrived at; then the remedy can be applied.
The Left never gets the diagnosis correct, doesn't understand the etiology, and, therefore, never has the correct remedy. They diagnosis "diseases" through the prism of what serves their political agenda, and when you do that, you have zero chance of understanding anything properly.
Gun availability is a problem, but it is not THE problem - and its quite easily shown. If gun availability were the problem, then Amish Country would be the most likely place to get shot and killed in the country. But it is one of the least likely places for that to happen. So, that would lead rational people to consider other factors.
But they won't, because politics is their god, and events like this are nothing more than opportunities to advance their ideology and agenda. They say, "Screw your prayers. That won't do any good. What we need is gun control!" And there it is.