The shooter had committed several very serious breech of the peace incidents and should have been jailed.
The cops knocked on the door in one instance, and walked away because he would not answer it.
Passing another gun law would have made no difference, but even so there were many serious warning signs that he was dangerous.
All ignored by the cops.
This was not a failure of the laws, it was a failure on the part of the cops and someone should be fired for it.
I am sure they will pay a heavy civil court settlement.
No, though the cops were incompetent, it happened because there actually are people evil enough to kill other people in this world.