Mass suicide occurs when a group of people kill themselves at the same time. This may be due to a cult practice, political protest, and a plan carried out by depressed people. Also, some groups who feel threatened resort to mass suicide rather than submit to an oppressor.
For instance, during World War II, the Japanese forces announced to the people of Saipan that the incoming American troops were going to torture the residents. In desperation, a number of Saipanese jumped off cliff sides.