I have been there, and done that. I've taught in urban schools for more than 20 years. There is nothing like the violence of a black girl-on-girl fight. You just don't see that violence with white girls, or with boys of any color. I suppose that someone will write a PhD paper on that someday.
But I will say this. When it comes to true psychopathic behavior, drop-dead evil behavior, in my experience that's almost always the white boys. Again, I suppose that someone will write a PhD paper on that someday.
Their behavior, black or white, is a damning statement on the collapse of parenting skills in urban environments. I, for one, do not buy these mothers' statements in the press, "They are a good kid just turning their life around." Baloney! With these "parents" always covering for them, they don't have a chance of learning right from wrong.
To address your observation of black girls exhibiting the greatest violence...I can attest to my professional observation as a polygraph examiner that black women were the meanest cats in the jungle. I taught Interrogation and always made my students aware of the most difficult subject to get a confession from was a cornered black woman...same techniques could break a black or white man but much different approach had to be used with a black woman...that’s what I found was so interesting about Anita Hill’s polygraph. Black women could lie through their teeth and show no physiological change making their charts show no deception.