@Invictus ... "How would any of those things (besides maybe parenting) have prevented this shooting?"
The issue isn't *this shooting.* The issue is shootings in general. This one is just going to reopen the Holmes/Lanza/Cho debate as to who should have a gun and who shouldn't. Having a gun should be a privilege, not a birthright for American citizens. There are plenty of crazy people among us that shouldn't have the right to a gun. These parents are on that list.
"He stole the gun from his parents, who, let's assume, followed the law and were perfectly entitled to own a gun. How would any law stop a situation like this?"
Would keep irresponsible parents from owning a gun.
"Obviously parent should do everything possible to keep their guns safe. But parents are only human."
Are you seriously defending the parents? They let their middle school kid get their gun. How is that defensible? They ought to be charged in the two deaths along with their child for neglect and potentially manslaughter because it is THEIR FAULT.
"The solution isn't taking away that right or imposing still more burdens on responsible, legal gun owners."
Sure it is. That ensures that the people that can have a gun are responsible with them because they get past the tests and the inspections and whatnot. They know how to own a gun.
"It's making sure as few people as possible reach the point where they decide to bring weapons to school and kill the people there."
Don't background checks and strict licensing regulations cover that? The rest of your post regarding a crackdown on gang violence I can largely agree with.
@Abge ... "Out of curiosity, what do people think would happen if this killer couldn't get his hands on a gun? Would he not have killed anyone, or would he have gone to one of the hundreds of sites showing people how to make bombs with household items?"
Given the materials, I could construct a dirty bomb, and that's a scary thought (not because it's me, but because it's a dirty bomb, arguably the most effective terrorist weapon outside of jumbo jets). Whether I could construct one that actually detonates correctly or not is irrelevant, but that's just something that we have to live with as far as I'm concerned because there's not a thing we can do.
@ILN .. "In Israel teachers can carry weapons to protect school children, USA should do the same."
Israel is not the United States (as much as they try to be). Regardless of civil issues that we all know about, terrorism is practically a daily reality in some regions. Not here, though we are gradually getting fed more and more propaganda to point us in that direction.