Actually after you reach a certain point of depravity, a human is very likely to lash out at even those that help it.

You can't possibly think that people are shooting because they maintain all of their mental facilities and they feel like it. Something has snapped. It has nothing to do with the fact that it is NOLA. The people there aren't used to natural disasters (nowhere in the US is) of this magnitude. After awhile some people begin to feel the government is abandoning them. Regardless of whether that is true or not the people will sink lower and lower into a state of mental disarray. I would chance it much moreso that it is a person that has 'snapped' mentally than a person that is just shooting 'because he's from a bad town'.