Excuse me for stating the obvious: Most black people are left wing and vote left wing, or has that point escaped you? Black Panthers, left or right wing? Left. This shooting was left wing oriented and no mistake.
I would point out that it could also be Islamic related. Remember, the guys who were just arrested a couple of weeks ago for wanting to blow-up airliners and a synagogue were also black. They were prison converts to Islam.
Not to buy blindly into a stereotype, but they have more of a gang-look to me. But, who knows.