Although I see your point and I also wonder what I'd do, but as far as ID'ing the perp while the shooting is going on, the perp in this case is probably the pimply-faced guy on the other end of the rifle.
It also looks like law enforcement were under orders not to arrest or interfere with the under 21 crowd due to the manipulation of statistics to qualify for federal/state funding.
If further investigation reveals that this was a national big bucks Obama rewards program to eliminate ethnic/blacks/immigrants criminal behavior statistics, I'm gonna puke.
The families of the 17 victims need to assemble an OJ-like "Dream Team" and tear the system a new a$$hole. I'd donate to that effort.