We have increasing numbers of frustrated people. These are especially frustrating times. We have easy access to guns and ammo, rampant undiagnosed mental health problems, loss of access to health care and medication, rising unemployment, homelessness and Bushvilles, higher rates of poverty, violent gangs, mafias, narco-terrorists, layoffs of cops and public safety officials, rapidly declining tax revenues at the state and local level. Add desperation to the mix, and people will react in very angry and violent ways.
Odd that John Robb of Global Guerrillas gave testimony to the House Armed Services Committee (pdf) Thursday in which he said:
"With the failure or weakening of nation-states across the board and the lack of ideological alternatives, people will shift their primary loyalties to any group that can provide them security and the basics of survival. These groups will span the gamut of gangs, tribes, criminal syndicates, militias, religious sects, etc. Many, if not most of these groups, will maintain and expand the interests both vigorously and violently. The worst version of this trend line would be the expansion of the criminal insurgency in Mexico into the US (through expansion of the criminal ecosystem more than anything due to ethnic identity)."
While not exactly on point, the example in your backyard is more proof of societal collapse, and is to be expected in the pressure cooker of 21st century America: armed and more dangerous than ever.
UPDATE: Three police officers dead in Pittsburg, shooter feared Obama Gun ban.