Anyone remember the DOJ report from February, 2012?
Turn to page 94. You'll find that since 1992, through the expiration of the AWB, with every state (except IL) allowing some type of conceal carry, school children are safer than anytime in recent history.
We can do some things to get that number even lower, but gun bans is not one of them.
http://bjs.ojp.usdoj.gov/content/pub/pdf/iscs11.pdf