Hold on a moment. Lets forget about color, sex and age of the two fighting. As a man, if ever in a fight of this magnitude, I am going to fight to win and win overwhelmingly. No different if it was an armed conflict, shoot or fight until there is no more danger.In this instance, white girl bit off a bit more than she could chew and got her ass handed to her. If this was 2 adult males, it would be considered self defense. Kids have a right to self defense as well and it looks like both were willing participants. This was not an ambush assault if it had, then a crime would have been committed. AS it is, just a simple case of self defense.
When you are bashing someone's head into the concrete, you left "self defense" behind a long time ago.
The smaller girl was absolutely no threat to the bigger one, and to characterize this as a "self defense" situation is just misleading.