You have to be kidding???
The problem is progressivism, which has infested psychology and caused societal upheaval.
Progressivism is Franklin School style social marxism. The point of social marxism is screw up society so bad it collapses. Literally.
This explains why the Left in general and Democrats particular are so frantic to kill off the middle class.
Now I am not normally one to suggest that feeding jews to Hitlers war machine was a good idea, or that the jews are the cause of all problems, but if we had given the members of the Franklin School back to Hitler instead of giving them sanctuary, modern progressivism wouldn't exist.
A ban on atheism would help as well.
The less social turmoil the fewer incidents like this occur, and there is a correlation between either the of number of progressives in psychiatry or the rate of anti-depressant prescription (take your pick) and the rate of mass murder.
Fact is about 2/3rds of US firearms are rifles. Only about 3% of all murders are committed with rifles. More people are killed with shotguns than rifles.
You can do the "assault rifle" dance all you want but there is no numerical justification.
Further, an AR15 is not an assault rifle. It is a semi-automatic weapon that people for hunting.
Even further, the MSM is deliberately misreporting to make AR15s look bad:
Observe How the Media Describes Stephen Willeford's Firearm vs. Devin Kelley
The media describes the weapon used by the Texas shooter as an "assault rifle" and the weapon used to stop him as a "gun" or "rifle". Both weapons were AR15 clones.
As far as the "only the police can be trusted with guns meme":
After Night of Drinking, F.B.I. Supervisor Wakes to Find a Woman Stole His Gun
An F.B.I. counterterrorism supervisor is under internal investigation after a woman stole his gun following a night of heavy drinking in a North Carolina hotel, according to documents and government officials.
Colorado Springs gun store owner says Texas gunman passed 2 background checks
And the mental patient who was dishonorably discharged for beating his wife and child and had a cruelty to animals complaint passed two background checks.