惨绝人寰[cǎn jué rén huán]
tragic beyond compare in this human world; a rare tragedy on earth; most shocking in the human world; so miserable that it can hardly be found in human life -- extremely pitiful; extremely tragic; extremely brutal:
例：惨绝人寰的暴行
atrocity of unparalleled savagery;
惨绝人寰之浩劫
terrible holocaust;
殖民者惨绝人寰地屠杀了成千的土著居民。
The colonists massacred thousands of natives with brutal and callous force.