Following the April 6, 1994 shooting down of President Juvénal Habyarimana's plane over Kigali, Hutu extremist militias began systematically killing Tutsi civilians. Over approximately 100 days, between 500,000 and 800,000 people died, primarily Tutsi and moderate Hutu. Radio RTLM directed killers to specific locations. Belgian colonial policies had imposed rigid ethnic classifications and favored Tutsis, creating tensions. The Tutsi-led Rwandan Patriotic Front captured Kigali on July 4, 1994, ending the killings. Two million refugees fled to Zaire. The UN ignored advance warnings and failed to intervene.