Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

I would say the shooter seems pretty interesting, by way of being completely uninteresting.  So far no prior history with law enforcement, no history of mental illness, a former accountant who lived in a retirement community.  All of this is obviously preliminary and new information will turn up.

it's impossible for me to comprehend how someone could do something so irreprehensible.

(Hmmmm, first time I posted, it didn't work.  We'll try again)

Not sure if this is appropriate here, but here goes....

I worked at an engineering office a few years ago with about 60 engineers.  One of the engineers I worked with for about three years was a kindly older gentleman (maybe 64-ish) who was an electrical engineer and had worked with the company for 30 years.  In the time I knew him, he never cussed and never raised his voice to another engineer.  Heck, someone who had worked next to him for 30 years told me that the guy had never even gotten a speeding ticket.  He had a wife, two daughters, and 4 grandkids.

I'd known him two years when his wife died.  Overall, he was a little sadder after that, but they had been married for over forty years, and she had died suddenly, so there was no prolonged suffering.  He seemed to be coping well and outside of the week he was gone for funeral arrangements, he came back to work and kept chugging through projects.

About six months after that, he didn't show up for work, and then was gone for two weeks.  His desk was quietly cleaned out, and it took me two months to find out what happened.

Turns out, he had been regularly raping his grandson about once a week after his wife died.  His youngest daughter had to turn him in to the police and he is currently serving a 15 year sentence.  His grandson will be in therapy for years to come.

The point to this story is, we all think that we are well adjusted people who could never commit the atrocities that we see on the news everyday.  Sadly, I've come to the conclusion that there are just a certain set of right circumstances (or wrong ones, I guess) that can just make you crack.  The mind can sometimes be a little fragile, and it's a lot easier than you think to convince yourself that the world is mad and you are the only sane one in it.

My neighbor (this morning) and I were talking about this (bump fire) walking our kids to the bus stop.   He's done a variety of tours in the Gulf, and he had a lot a few interesting comments about this LV shooting.     Immediately suspected it was bump fire, and said the (likely) policy of turning on the flood lights, made matters worse, not better for the crowd, and then said how, while he understands why people do it,  people freezing and not moving is always the worst choice in a situation like this.

The shots I heard on the news did not sound like full auto fire.  More like someone pulling the trigger as fast as possible but too regularly spaced for that.  What came to mind was a paddle crank I saw on someone use on a 22 semi-auto once.

The bump fire tactic no doubt compromises the accuracy of the shooter greatly, but the effect (the sounds of automatic fire) is achieved and presumably the objective.

It seems unlikely that this shooter would have cared much about compromised accuracy.  From what I have read so far it does not appear that there were any specific targets and he was shooting at a very large mass of people.  If his goal was simply body-count it would seem that the speed of the fire would have been important to him and the accuracy not very important since hitting someone with a shot would be nearly assured when shooting at such a large mass of people.  

temp... have no idea on the sound, but I thought it was said they were fully automatic weapons...????  or is a paddle crank a way to make a semi into an automatic?

The news media is notoriously ignorant when it comes to guns.  If someone in law enforcement said weapons were "Fully automatic" I would give that a bit more credence but even there they may have been speaking too soon and just basing that on the sound.  
On a typical fully automatic weapon when the bullet gets close to the muzzle (end of barrel), some of the gasses that are propelling the bullet are diverted down a separate tube when then pushes a plunger.  That plunger then ejects that round, another round is loaded (automatically), and the gun immediately fires again restarting the process.  
Bump-fire and paddle crank are methods of increasing volume of fire without actually having a fully automatic weapon.  
Semi-Automatic:
When you fire a semi-automatic the gun automatically ejects the round and loads the next one but does not fire.  With a semi-automatic you still need to pull the trigger for each bullet.  
Bump-fire and paddle crank are systems to rapidly pull the trigger.