&quot;These kinds of events are sad for the people involved, but probably not worth spending time trying to figure out, as they are exceedingly rare.&quot;<p>These events aren&#x27;t exceedingly rare. Quite the opposite. In fact, the San Bernadino shooting wasn&#x27;t even the only mass shooting in the US on December 3rd. IIRC, there has been one mass shooting, on average, every day since the Sandy Hook shooting in 2012.<p>More info: <a href="http:&#x2F;&#x2F;www.npr.org&#x2F;sections&#x2F;thetwo-way&#x2F;2015&#x2F;12&#x2F;03&#x2F;458321777&#x2F;a-tally-of-mass-shootings-in-the-u-s" rel="nofollow">http:&#x2F;&#x2F;www.npr.org&#x2F;sections&#x2F;thetwo-way&#x2F;2015&#x2F;12&#x2F;03&#x2F;458321777&#x2F;...</a>