I remember seeing fights in school back in the early 1960s. Two white boys would go at it. Everyone would gather around and watch the slugfest but no one would jump in. When the police showed up the crowd broke up like a covey of quail.
White and Black or Hispanic was different. Saw a white boy and a Hispanic almost get in it, and another Hispanic got behind the white boy with a knife, but NO ONE with a knife got behind the other Hispanic fighter . The fight did not start.
A friend of mine who went to school in Mexico told me, "You pick on one bean you gotta fight the whole burrito."