Between April and mid July 1994, between 800 000 and 1 million Tutsis and moderate Hutus were murdered by Rwanda's Hutu regime. The catalyst for the genocide is usually identified as the shooting down of an airplane carrying Rwandan president Juvénal Habyarimana and Burundi president Cyprien Ntaryamira on April 6. It has never been established whether the plane was downed by the Rwandan Patriotic Front (RPF, Tutsi) or Hutu extremists, though Amnesty International reports it was Hutu extremists who believed Habyarimana was about to implement the Arusha Peace Accords that had ended the civil war. The immediate consequence was a dispute over who would assume political authority. The UN Force Commander Lieutenant General Dallaire argued that in terms of the Arusha Accords, the Prime Minister should take office. The Rwandan Armed Forces disputed this, assassinated Prime Minister Agathe Uwilingiyimana and murdered the Belgian soldiers assigned to protect her. The genocide of Tutsis and moderate Hutus ensued with roadblocks being set-up to verify individuals ethnicity and the assassination of Tutsi and moderate Hutu leaders. While the genocide was ongoing, the civil war between the RPF and government forces reignited. Ultimately, it was the rebel advances and a victory in mid-July that ended the genocide. The Tutsi military victory prompted an estimated 2 million Hutus to flee Rwanda, fearing reprisals and revenge. Hutu refugees fled to Burundi, Tanzania, and Uganda, but mainly to Zaire (now Democratic Republic of Congo, DRC) in one of the largest migrations of people in history. Thousands of Hutus died of dysentery and cholera in refugee camps. During the following decade, several hundred thousands were repatriated to Rwanda from the DRC and Tanzania. Arusha, Tanzania is the seat of the UN sponsored International Criminal Tribunal for Rwanda which is still investigating and prosecuting perpetrators of the genocide.
References

Amnesty International, (2010), “Rwanda”, from Amnesty International, [online], Available at www.amnestyusa.org [Accessed: 14 July 2014]|Human Rights Watch, (2004), Leave None to Tell the Story: Genocide in Rwanda, from Human Rights Watch, 01 April [online], Available at www.hrw.org