Explanations and SuchOriginally Posted by Shur2gal's Version
"Beyond description" was a little too odd for my liking (although I guess it's up for debate, seeing as it wasn't too bad), but I found "beyond devastating" much better because 9/11 was, indeed, devastating. At least, any native American would describe it as such. I took out the other sentence since it was only a follow up to "beyond description" and the new sentence doesn't need it anymore.
I replaced "howls" and "growls" with "screams" and "cries" since it sets the mood (at least, for 9/11) much better than those odd word choices. I replaced 911 for "nine-eleven" because 911 sounds more like the phone number, and no formal writing would use it. So I went for "nine-eleven" instead, although you COULD technically use 9/11.
"Existing in people's mind" is really, really unnatural. Usually they can be "[be] remembered as / by". Or, you could use "known as" as well, which is what I opted with, but you could use what I referred to earlier and it would be correct and natural all the same. (I put brackets by "be" because you would need to put that word after "to" in my version of the paragraph for it to be correct.)
I didn't get "do the same". Are you referring to the people who crashed the planes? If your referring to the USA (which makes more sense, since they were mentioned in the previous sentence), than you would have to specify what they were doing (since, according to the previous sentence, they've managed to remain "untouchable," so how would they be "doing the same" when they're already managing it?). I changed it to fit, and kept your last sentence.