This, the shooting(s) today, the ones coming tomorrow and in the days ahead, all have the same roots...
Most children today are going to be raised in single parent homes - @ 80% of blacks and @ 50% of whites (may be higher now).
So, those kids only get a half measure of love, role modeling, etc. The idea of unconditional love doesn't exist for them.
Even those being raised by both parents, a lot will have the same problem. Mom AND/OR Dad will spend the majority of their time per day working to buy the newest "stuff". Not to pay the bills, but to buy 80 inch TV's and 80K vehicles.
So, they'll pawn their children off to strangers to raise the majority of the day. In these "daycares" they will teach them how to talk, walk, potty train them. All the big events in life. Mom picks the kid up, takes him home, puts him in front of a screen to occupy him while she goes about getting supper, etc. The daily routine...
Meanwhile, in front of that screen, the kid will witness @ 5K acts of violence before reaching kindergarten age. Murders, rapes, assaults, disrespect, you name it - because you are letting people into your living room that you ordinarily wouldn't allow through your front door.
Then the kid wants a screen of their own, so he gets an XBOX/PLAYSTATION?WHATEVER for Christmas. The games of today are not like the ones on Atari 40 years ago. The ones today are far more lifelike, more like a simulator than anything else. So much so that "killing" becomes routine. Emotionless. Easy.
Then, they get a cell phone and a computer and can't converse with anyone except over a screen. Anything that disagrees with their rigidly held beliefs causes them anxiety. Add to that the kid gets honor roll because education has been dumbed down to that point - its participation trophy in education as well as sport.
Then, life hits. They get a rude awakening. There's no mommy to take care of it anymore. The boss (whoever that is - literal boss, teacher, preacher, etc.) simply fires you, disrespects you in your eyes, so you revert back to your training - except this time with a real gun.