Why is it headline news? It happens all the time.

[Lilith7]

I think most of the power and influence of the NRA is just that they keep ramming the fact that making all the laws you like won't make a problem go away and so many people understand that and support the stance.

Personally I think legislation is the only way they can fix the problem.  Clearly the behavioural change needed in a certain sector of US society will not happen on its own, therefore the change required needs to be properly targeted with appropriate legislation and effective enforcement.  Mass shootings of this scale is a uniquely US problem and the status quo is not working...

Having said that deeply embedded behavioural issues of this nature could take a generation to change, so they need to start sooner rather than later...

I think its crystal clear that America can't continue on down this path; they need change in their attitudes & laws to both guns & violence & I agree that its not something which can be changed quickly. 

They're all going to have to recognise the  need for change first & that's likely to take time - so more people will die in this way. 
Perhaps they could start by teaching school kids empathy; it might or might not help but certainly can't hurt.