Bad guys will always have guns. You can't legislate that away.
There's enough empirical evidence from other countries and from our own municipalities (like Kennesaw, GA) to show that guns, in the right hands, are a strong deterrent to crime. You'll reduce attacks in schools by putting armed good guys between the crazies and the kids. We know it works. It's worked in Israel and Thailand. Look at the reduction in airline highjackings, since armed marshals were introduced. We already know the answer to how to stop guys who would shoot up a school full of kids. We know what works. So, let's stop using this Sandy Hook tragedy to advance the liberal's agenda to ban guns and address the real issue at hand ... how to protect our kids and schools.