General descriptions:
* Horrific acts of violence: This is a straightforward and neutral description.
* Heinous crimes: This emphasizes the moral wrongness of the act.
* Acts of barbarity: This highlights the cruelty and brutality involved.
* Shocking acts of cruelty: This emphasizes the unexpected and disturbing nature of the acts.
* Acts of inhumanity: This focuses on the violation of human decency and morality.
More specific descriptions:
* Crimes against humanity: This is a legal term that refers to widespread or systematic attacks against a civilian population.
* War crimes: This refers to acts that violate the laws and customs of war.
* Mass killings: This specifically refers to the killing of a large number of people.
* Systematic persecution: This refers to the deliberate and organized targeting of a group for harm.
* Acts of genocide: This refers to the intent to destroy, in whole or in part, a national, ethnical, racial or religious group.
Ultimately, the best phrase to describe "atrocities" will depend on the specific context and the emphasis you want to convey.