One of my coping mechanisms involves going radio silent for a while, keeping my head down until I know more and I'm calmer. This is a mechanism I learned in 2001, because my primary reaction is to analyze, guess, and rant. So know I just rant to my wife and keep my mouth shut the rest of the time, soaking up information.
Most things I learn to let go and not stress about, but one of my friends posted something on Facebook which I've been putting some thought into. He wrote, "Such a sad event. We live in a world and culture where violence is not just normal, but seen as entertainment - so how can we wonder why people would turn to violence to make a statement?"
Historically, though, our society is quite exceptional, not for how we embrace violent entertainment but for how we reject violent action. The last major bombing in the US was over a decade ago. The last real riot was the LA Riot. Political assassination has been effectively shelved as a tool.
More poignant, violence as a political tool is an ancient tradition, from the burning down of Druidic groves to the assassination of Julius Caesar, from the crucifixion of Christ to the riots from the early days of Labor. Violence has a long and storied tradition in politics and religion, and that doesn't even include wars, which are inherently both violent and political.
In a more recent perspective, consider the Taliban. The IRA. The CIA. The PLO. Jihad. Subway bombings in London, Spain, Japan. International and domestic terrorism are common in many nations today.
If anything, our country has been blessed by a relative shortage of political violence and terrorism. Combined with the effectiveness of the FBI in combatting terror, I've come to two conclusions: we're really lucky AND current society is doing something right when it comes to violence.