If these were white on black, within the first inkling that this was a national activity, or even more than a coincidence, the entire government and media would have gone into action, there would have been federal and state task forces, whole plane loads of federal agents and investigators flying into the hot spots, emergency legislation, it would be treated like a deadly plague virus being unleashed, all stops would have been pulled out.
As it is, it is treated like some odd weather phenomenon, mentioning it almost as an oddity, or a quirk of big city living.
You're right ansel.
Also these types of attacks have been going on for years. The press, FBI and police weren't able to hide them once the perps started downloading beatings on YouTube for bragging rights.