More or less gun-free zones?

Here is a study completed by John Lott of the University of Maryland and William Landes of the University of Chicago in 1999: http://papers.ssrn.com/sol3/papers.cfm?abstract_id...

In summary:

"Our results are surprising and dramatic. While arrest or conviction rates and the death penalty reduce normal murder rates, our results find that the only policy factor to influence multiple victim public shootings is the passage of concealed handgun laws. We explain why public shootings are more sensitive than other violent crimes to concealed handguns, why the laws reduce both the number of shootings as well as their severity."

So in other words, their extensive study indicates criminals who engage in public shootings prefer unarmed victims. And where better to find unarmed victims than in a gun-free zone?

From the high school shooting by Luke Woodham in Pearl, Miss., to the New Life Church shooting in Colorado Springs, Colo, to the 71-yr old who chased off two thugs in an armed robbery (caught on tape here: http://www.youtube.com/watch?v=8Cbtmlai5VQ), to the Mayan Movie Theater shooting ..... proof is everywhere that guns, in the hands of law-abiding citizens, are the greatest defense and protection against an unsuspecting populace.

So, given the facts of recent history, is it better to have more or less gun-free zones? And feel free to elaborate on your opinion.