No amount of gun control that is realistically possible in the US would have stopped this. There are simply too many guns existing in the country for making it harder to buy them to have much affect on a criminal's ability to get a gun. Look at automatic weapons for an example. It's been illegal to buy newly manufactured ones for almost 30 years, and you can sill buy them relatively easily. The price is 4-5 times what it used to be, but they're available. You could ban gun sales to civilians completely, and unless you went around taking away the guns that people already own, it would not make it significantly harder for someone to get access to a gun, even if it was illegal. And taking people's guns away is realistically never going to happen in this country. Guns really aren't the issue here though. You could take away every gun in America, and things like this would still happen. That's because crazy people don't need guns to do things like this. Just look at Ted Bundy, Jeffrey Dahmer, Timothy McVeigh, Benjamin Atkins, etc.
Hopefully the wounded recover okay, and the guy that did it gets the death penalty.