Not to defend looters, but put yourself in there shoes... You got no home, you got no food, you got no water, there's no for sale stores. There's no banks to get money. Sure there are people taking non food, but you can excuse clothing. As for electonics etc, frankly the city is a loss, most of this stuff is likely so damage it will never work anyway. Bush is too busy on "vacation" to send supplies. Hell, he can parachute food to people in Iraq, but f his own people... What would you do?
As for only blacks, there has been video of whites, granted not as many, but the area has a large black population. Many of the poor, that lacked resources to leave were minority.