Cases like this are especially horrific and tragic.
Once again, one sees the total inability to prevent such acts due to current laws and practices regarding dangerous persons with mental illness.
The quick response by some is to say that all firearms need to be "controlled" or that laws should be passed to prevent someone with mental problems from obtaining one.
As an example, ALL states have laws which prevent selling of firearms to persons with various types of legal restrictions - BUT only those restrictions such as Felony conviction records can be accessed by LE doing background checks. Any kind of mental health problems are privileged information covered by HIPA regulations, and therefor NOT available in a back ground check, unless mental issues previously led to some sort of felony conviction - OR if the person applying for a firearm purchase checks the block which says he/she has mental issues. Of course the person with mental issues is usually the last person to recognize or admit it.
What is seldom stated is that legislation needs to be passed regarding the establishment of secure mental health facilities and means of enforcing existing laws regarding persons identified with mental problems. Some jurisdictions do have "Mental Health Court" programs which deal with persons who have mental issues. Unfortunately, a "requirement" for someone being admitted to this type of program is that they have already committed some sort of crime.
The Sandy Hook School Shootings is often mentioned in discussions about terrible mass killings. A very detailed investigation was done on this case and the findings presented in a long report, which few have ever read. I include it below as a link.
Note that in the introduction, the authors are quick to show their hand as "anti-gun" people, and in several places in the report they state that assault type weapons with high capacity magazines were the primary cause of the tragedy, while downplaying all of the many mental health issues which were, in fact the real primary factors.
One can see in this report that throughout the killer's life, the same school system repeatedly ignored or downplayed significant mental issues during his IEP review meetings, and that no assistance was forthcoming from the community health system after he was graduated from high school.
LINK:
www.shac.ct.gov/SHAC_Final_Report_3-6-2015.pdf