If you heavily restrict guns, for the civilians, which is essentially what they are doing, then the wrong people would be getting the guns, which would be the crazed criminals. Police can't stop everything. Besides, even with gun restriction, and assuming none of the murderers out there had access to said weaponry, one can kill just as easily with a bow ad arrow, knife, rock, animal bone, or fist. I'm not saying gun control isn't an option; But gun registration isn't going to work, since that's the Government's first order of business. If you were a homicidal maniac with a gun collection, would YOU register your guns? And nevermind the fact, that if we do get rid of the second amendment because of this, it STILL won't solve gun issues, and we'd have given away one of our constitutional rights as Americans.
In any case, and my apologies for the political thing I just said, my heart goes out to the family and friends of the deceased.