"In the end, only one question remains: How gullible are you?"
Source - http://cluborlov.blogspot.ca/2017/10/the-limits-of-gullibility.html
If you read all of Orlov's essay, you may get the impression he thinks the whole thing was a hoax. I do not - there WAS a shooting, people DID die, hundreds WERE wounded, and the only real questions are "who did it?" and "why?"
As to why all these witnesses described things in the same manner, I would posit that it's because they all watch the same TV shows and movies which plant the same images and phrases into everyone's head. The "entertainment" industry controls both our morality AND our language, so I would put the blame (if that's the best way to describe it) at their door.