It's really, really horrible. A co-worker did point out to me a simple fact. How many kindergartners are there in America today? And we have 18 die in a tragedy. Statistically speaking it's insignificant. Those really are the cold hard facts. As tragic as it is, it's statistically insignificant.
I don't know what the solution is. It's certainly not more laws. It's already illegal to bring a gun on to school property. That law didn't stop this at all. I don't know what other laws would've prevented this.
I really think the problem is the culture we live in. We live in an extremely violent culture that glorifies violence. It shouldn't be too surprising that people would lash out with violence since the culture we live in legitimizes that as a valid response.