I think you point out the distinguishing characteristics of the perps if there are any. Being white in mid 20th century America was not a distinguishing characteristic, just as wearing a crucifix was not a distinguishing characteristic but wearing a yarmulke was. (I'm Jewish, BTW.) A report wouldn't say a perp had no obvious scars or tattoos either.
ML/NJ
It is true that two of the robbers escaped from the scene and so a physical description is called for. But saying they are negroes doesn't narrow it down much. What about height, weight, clothing, apparel, and yes, scars or tattoos.