No matter how you slice that its an ugly ending. You need to worry about ricochet for the dozens of bullets, cross fire and what if someone "got to the party late" and took one of the good guys to be a bad guy. Oh my god it would be a disaster. I think I'll start taking the position that more gun control is needed from here on in.
This 'shooter' used fake ID's from time to time and had a bunch of wigs. He also changed his licence plate. Clearly we also need better bio-metric ID and tracking in cars (and, as always, more gun control and mental health surveillance.) I wonder how many millions of dollars the 'victim's' families and the cops will be receiving from this one in order to assist in their 'healing'.
We also need real justice. You hurt someone by breaking his arm... your arm is broken, plus you need to pay to make him well. You kill someone... you are executed, after you have been forced to pay off his family.
This doesn't include accidents that are truly accidents. These would be handled differently.
A theater shooter would act differently if he knew he was going to become a literal slave to pay off anyone he killed or harmed, before the same thing was done to him that he did to others.