The 30 dead in one apartment building was striking to me as well. I immediately thought to myself that the death toll must be well up in the hundreds. That being said, I will be quite shocked if there are indeed "thousands" dead in Mississippi. In fact, I'll be surprised if there are over 1000 dead in MS. Hurricane Camille killed some 21 people in just one building (the Richelieu Apts), but there were still 'merely' 143 deaths on the Gulf Coast. Granted, the region is much more densely populated these days and Katrina tore a wider swath of destruction, but still..
It's not at all unusual in a hurricane for one neighborhood to be totally devastated by surge or wind and the next one over to be more or less fine. A lot of this has to do with all the tornados that touch down. So, for what it's worth, my guess is that the person reporting these figures is in a particularly hard-struck area and is incorrectly extrapolating his experience to the region as a whole. Maybe I'm in denial, but that's just my hunch!
I do expect over 1000 dead in New Orleans.
Neighborhoods in a 40 mile swath were blown away. It was not a hit a miss thing. It was, hit, hit, and hit again. Anyone still there who lived was lucky. It was not an isolated thing. We will eventually find out how many of those seeking the Darwin award remained.
THe east arm of Katrina had over a 125mi radius of hurricane size winds. Camile was an ~50mi radius. This 'cane had ~5X the energy of Camile also. All along that arm the average surge was 20-22 ft and the wave height out was 40ft. That's like a 125mi long tsunami wacking the shoreline.
That's why only slabs are mostly left from Slidell to FL, all along the shore. One of Biloxi's big beach front hotels was left standing with signs of a wave crashing into it at over 40 ft up. The east eye wall was ~ Bay St Louis. That's the highest wind velocity and correspondingly highest waveheight.