It seems to me that this disaster is so much larger than anyone anticipated that its truly overwhelming. What generally happens in such an emergency is that the local government begins to organize rescue and relief, which is followed up by the state authority and the federal departments come sweeping in after once things are somewhat established.
However, the local response was completely overwhelmed, and its leaders (the mayor) incompetent. (The evacuation call came way too late and he is feeding the crowds by demanding help but actually doing little else, including telling the police they are on their own, rather than taking charge and trying to organize at least to some degree.) I'm not sure what is happening at the state level but it also seems to be slow and poorly prepared as well. Because these local sources are almost non-existent, the length of time to organize federal relief seems to be even that much slower. (I am not excusing anyone, simply observing that it takes a while) However, the biggest compounding problem is the fact that nobody expected there to be 100,000+ people needing to be rescued. This many people gathered in one small place in a virtual destruction zone is a nightmare for everyone.
While part of me wonders why nobody among these crowds seems to stepping up and assuming a position of leadership (organizing body removal groups, supply gathering missions, etc.), I am finding it difficult to understand why a couple C-130's filled with supplies can't fly overhead to drop in MRE's, water and a few bare essentials as temporary relief. That is the part thats baffling to me. I am willing to excuse the length of time it takes to organize an effort of this magnitude, but I am shocked that we can't drop in some supplies.
Of course, maniacs toting guns and shooting at rescue workers certainly doesn't help (besides the fact that it is about the most absurd thing I may have ever heard of).
PS. My assessment of the mayors actions could be completely off base, as obviously I am not there... its just the impression I am getting.