EDIT: I see my post is being downvoted. I know that it may come across as insensitive to immediately leap to the gun control debate, but frankly I'm more angry than upset by this news. How many times does it have to happen? We have a good 48 hours of emotional outpouring and then everyone forgets it ever happened.
Was the Oklahoma-city bombing a wake-up call for "explosives control"? Was the 2009 Chengdu bus-fire (http://en.wikipedia.org/wiki/2009_Chengdu_bus_fire) a wake-up call for diesel control? Was the Osaka school massacre (http://en.wikipedia.org/wiki/Osaka_school_massacre) a wake-up call for knife-control? Was the 2012 Toronto mall shooting a wake-up call for gun-control in Canada, which already has extremely stringent gun-laws?
It's all too easy to blame the gun in these situations, but guns are just tools, as are knives, and diesel fuel, and even explosives.
It's not the gun. It never was the gun. It's the person.
So what if it's the person? How can you find those people and stop them from getting guns? All the people who knew the shooter in the Oregon mall shooting a couple days ago said that he showed no signs of being anything other than a kind and friendly person. He showed only a marginal interest in guns. But that could describe hundreds of millions of Americans. You would never be able to find the ones that might do this and make sure they don't get guns.
Ultimately it's impossible to be knowledgeable of the bad intentions of every single warped individual on the planet. And some of those folks will have the capability of harming people, perhaps many people. Look at 9/11 as an example of how a handful of well trained and highly motivated individuals armed with only box cutters were able to take control of jumbo jets and ram them into buildings and kill thousands. That's an extreme example but it's worth remembering, because there are many, many examples of similar situations. Look at the unabomber, for example. A brilliant loner who was able to fashion bombs from household materials in a shack in the middle of nowhere and kill several people. Or look at all of the other bombers throughout history. You can't legislate away the ability to build bombs, they're already illegal, but anyone with enough knowledge and a little money can make them and kill people. The same goes for arson, which kills hundreds of people every year.
In my view the solution is not to try to disempower the entire populace by taking away guns and hoping that this disempowers the bad guys enough to make it that much harder for them to kill. I think that the better solution is to empower responsible individuals to act in their own self-defense and in the defense of others. I think it's also worth concentrating on social and cultural changes which make our society more accepting and hopefully make the creation of these violent individuals less common, but that's a much harder problem to tackle.