The usual talking heads will be on the airwaves blaming the entertainment industry soon enough. I don't know if anyone can ever find rhyme or reason in the mind of someone deranged enough to shoot a celebrity, a politician, or a group of innocent people.
I happen to live in one of the towns where a theater shooting occurred at a screening of The Warriors in 1979. That cast a long enough shadow the city asked the cable company to black out an HBO showing on Halloween two years later.