In the large scheme of things, 12 KIA and 36 wounded is not significant, considering that the Salafist AQ in Iraq killed over a hundred people that same day in Iraq: or the 19,000 killed in the ongoing Salafist Syrian Civil War! It's just that we as Americans aren't used to such mayhem in our own back yard! This will change!
As we have turned our backs on, and conceded victory to, the violent Jihadists in the Middle East, they will be emboldened to bring their offensive Jihad against the unbelievers in their own land, the "Dar al-Harb" United States. Sooner rather than later, the Aurora-style attacks will become commonplace. The only difference will be that the Salafist-apologist Media will continually spin the violence as the fault of the American people for "oppressing Muslims", (which is, by definition, not immediately turning our government over to them!)