I wasn't going to write on this event, as only one was killed. My friend the conservative blogger Promethean Antagonist suggested I take a look. He sees the assault on Republican congressmen by a homicidal Bernie Sanders supporter as "first blood" in a new American civil war. So I look a look, and found that transiting Uranus was merely hours after an exact square with the US (Sibley) Pluto. Uranus is very much a "spark" astrologically, and Pluto is very much a "powder-keg". Let's hope that cool heads prevail.
There is a very weak Bloodbath Formula on the event chart, and for the concurrent shooting at a UPS facility in San Francisco.