And, this page proves it: http://www.fbi.gov/about-us/cjis/ucr/crime-in-the-u.s/2010/crime-in-the-u.s.-2010/tables/10shrtbl06.xls
From those FBI figures, blacks are ~10 times likely to murder another black, as a white is to murder a black.
Also, from those figures, you will see blacks kill whites on a 2-to-1 ratio.
The blacks are well described by those figures, proving the blacks, in the USA, are a murderous bunch, and deserving of your attention and caution. From these statistics, you can see that blacks attacking like mad dogs are going to face lethal action from citizens protecting their lives! It is like DUH!