Uh, no, if several hundred thousand people were murdered, that would be a massacre.

If they left because they were afraid of being murdered (or otherwise violated in their physical safety), that would be ethnic cleansing.

Do you not believe this applies to those who left Detroit, or Algeria? Really? Is it not the case that every country and major city outside East Asia contains areas where residing would endanger you? Including... most of Detroit? Could you seriously be this good and innocent a person?

Note also that it takes a lot less physical menace to drive out Ward and June Cleaver, than Dylan "YOLO" Hipster. Of course, Ward and June were privileged...