Meh. People, not a big fan. Humans kill their own all the time not just other groups. In fact, Governments are the biggest murderers of all time. It's called democide. Perfect examples of this would be Joseph Stalin, Mao Zedong, Pol Pot. It is very sad how horrific we humans can treat each other.
But note that the vast majority of "man's inhumanity to man" is from people following the orders of a perceived "authority," rather than people acting from their own malice.
'We' humans? Please speak for yourself ...