It should be all quite familiar to us now that people with some forms of mental illness - the kinds who are obsessed with violent video games - are a threat to the public. Such as in Newtown, CT. We've actually seen this pattern since Springfied, OR back in the '90s before Columbine. At times - probably much more frequently than killings though I don't have proof beyond what I know of mental hospitals - their psychiatrists or other mental health professionals recognize people who are dangerous to the public before killings happen and they are shipped off to state hospitals.
Sadly, sometimes laws are written such that mental health professionals' hands are tied and they can do nothing truly preventative until after a crime is committed. This varies by location. Since the days of long-term psychiatric hospitals have ended, there is no where to treat people who really need that level of care. It is very difficult for both the mental health provider community and the state to work together on this, and the awareness and involvement of the community would be helpful in this process: excepting in inpatient circumstances, professionals are not continually aware of patients' current state. Meanwhile we can thank the civil rights movement for protecting the rights of killers to kill (sarcasm). Actually, some progress is being made in this area. At least in some places.
Politicians blame guns instead of inadequate treatment of mental illnesses, but why not the still absurd but probably more effective regulation of violent video games? Guns are what stop these people from shooting even more people. Every time. It really doesn't matter in what way guns are illegal or legal for someone determined to kill to find a weapon. It does matter that people who can protect themselves and others prevent additional injury and murder. I talked more about that here.
Mass murders are not the norm, nor are they on the rise according to at least one researcher. The difference is in our media. Now with Twitter, FB, the Internet, etc. people hear about these stories more quickly and more often. It's also no surprise that a sensationalist media is eager to tell the most horrific stories.
It should also come as no surprise that the media isn't talking about how we can better care for those mentally unstable people with violent tendencies - just spouting whatever the liberal politicians are saying about gun control. At least, this is no surprise to me. I'm guessing the people who study these topics are frustrated by the media's lack of interest in effective care and prevention. Sorry, folks, effective prevention isn't part of the political agenda.