Interestingly enough, the OP has it right. If somebody had have had a gun or some other weapon capable of firing a projectile, then perhaps not as many people would have died. Ever wondered why crime rates are low in the Texas countryside? Why people still feel comfortable keeping their doors unlocked?
Or in Columbia, which is generally a wild nation, the emerald mines are perhaps one of the safest places you can find in the nation. The reason - it's similar to the Wild West.

Everybody totes a gun, and everybody protects themselves.
On the other hand, if somebody has a gun and nobody else has a gun, who is going to stop the gunman?
Lets face it, there will always be guns, and there will always be gunmen. So I see no real alternative to permitting everybody of reasonable responsibility to have a firearm.
Or, better yet, establish a rotating roster of obligatory enlistment, as Switzerland does - we never hear of infamous crimes in Switzerland. They respect the gun, and each responsible adult has one. As a result, violent offenders are rare.
In this society, the majority of people do not respect guns or treat them as a normal, every day implement... Since it's difficult to obtain them, there is mystique surrounding them and a surreal feeling of power. And then when somebody unstable or immature experiences that power, people die.