Unless the person holding the gun has the intellect to rationally consider the conquences of his/her actions, no punitive deterrent will decrease this kind of thing. If you want this kind of thing to stop you have to have more people with a solid ability to weigh the consequences of their actions before taking those actions. In short we need more education! People who know how to think, are much more likely to think about the pros and cons of their actions.

Wilmington's great crime fighting operations should focus on the classroom: http://apps.unitedway.org/forecaster/