United Nations Assistance Mission for Rwanda
In a genocide, many or all people in a group are killed because of their ethnicity, religion, or political opinions.  In the Rwandan genocide, members of an ethnic group called the Tutsi (abatutsi) were killed because of their ethnicity.  The killers were extremist members of another ethnic group called the Hutu (abahutu).  The Hutu killers also killed other Hutus whose political beliefs were not as extreme as theirs.