There will always be troubled children and adults who need as much extra help as we can provide, and we can probably do a better job as a society and community to help the parents and relatives of those individuals.
But it's inevitable that no matter how much help we provide, there will always be those who go over the edge; and not all of those who do are going to be obvious potential perpetrators. We've often read of the "quiet" ones, the nonthreatening boys and men who for whatever reason explode. The obvious, most immediate and easiest way to limit the destruction they can cause is to eliminate access to assault rifles, automatics and semiautomatics. Under a perverse interpretation of the Second Amendment we are providing potential mass-murderers the tools to carry out the deeds they might otherwise be limited to merely fantasizing.
We don't know why this last killer did what he did. Perhaps his mother overslept and failed to make his Ovaltine that morning. What we do know is that the mother apparently devoted her life to trying to care for her son. It wasn't lack of support, love or attention that set the young man off. The mother's fatal mistake that cost her not only her own life but the lives of 26 others and her son's was keeping four violently effective weapons within easy reach.
The boy could have had his fit of rage, and maybe even set out in his car to run somebody over. He could have slit his mother's throat and then gone after the letter carrier.
But he would have had a far more difficult time killing 26 more people and then himself if those inexcusable weapons hadn't been at his disposal.