Aside from the heroes all coming here to claim that if they'd been there packing it would have somehow helped, here are some actual facts.
Approximately 32,000 Americans die each year from firearms. By percentage, that's more than twice the death rate of any other developed country and eight times the average of all developed countries combined. The incidence of death by firearm in the United States is about 70 times the rate of that in developed Asian countries. The United States also has more guns per capita than other developed country.
The five states with the most firearm deaths are five of the most heavily armed: Alabama, Mississippi, Lousiana, Alaska and Nevada. More Americans die from suicide by firearm than from homicide. Young people aged 15-24 are the overwhelming majority of death by firearm. In most countries, the majority of shooting victims are male, but the United States has the highest incidence of women being shot.
The idea of more guns being the solution apparently appeals to people who like guns, but none of the facts point to that being true. Where there are more guns, more people die from guns. Where there are more pencils, people do more writing.
Source:
http://www.uphs.upenn.edu/ficap/reso...ection%201.pdf