Between April and July 1994, extremist Hutu political and military leaders in Rwanda organized the systematic killing of an estimated 800,000 to 1,000,000 people, overwhelmingly ethnic Tutsi and moderate Hutu, in a genocide recognized as such by the United Nations. As the Tutsi-led Rwandan Patriotic Front advanced and took power, roughly 2 million Hutu civilians, including many genocide perpetrators, fled into neighboring Zaire (now the Democratic Republic of the Congo), creating one of the largest and fastest refugee flows of the late 20th century, concentrated around Goma and Bukavu. Conditions in the refugee camps were dire, with a cholera epidemic killing tens of thousands within weeks. In 1996–97, a Rwandan-backed rebellion (the First Congo War) forcibly dispersed and drove home much of the refugee population, while armed remnants of the Rwandan genocidal forces remained in eastern Zaire, fueling subsequent regional conflict.
Hutu-extremist government forces and Interahamwe militias killed Tutsi and moderate Hutu civilians; the Tutsi-led RPF's military victory triggered a mass flight of Hutu civilians and former perpetrators into Zaire
The August 1991 census recorded 7,157,551 people. Its ethnic categories — 91 per cent Hutu, 8.4 per cent Tutsi — were themselves a product of the identity-card system that made the genocide administratively possible, and the Tutsi share is widely regarded as understated. Between April and July 1994 roughly 800,000 people, overwhelmingly Tutsi, were killed; the exodus to Zaire and Tanzania in July 1994 moved about 2 million, overwhelmingly Hutu.
Alison Des Forges's Human Rights Watch study estimated at least 500,000 Tutsi killed; Britannica and most UN accounts put the toll at more than 800,000; the Rwandan government's own census of victims returned 1,074,017, a figure some demographers regard as high relative to the pre-genocide Tutsi population. Not included in this range are the tens of thousands of Hutu refugees who died of cholera in the Goma camps in mid-1994 and the deaths of 'probably tens of thousands' of Hutu in the 1996–97 attacks in Zaire recorded by the UN Mapping Report — separate events with separate and contested counts.
The ICTR in Akayesu (1998) found systematic killing of Tutsi civilians and systematic rape of Tutsi women amounting to genocide, and the 2010 UN Mapping Report documented massacres and summary killings of Hutu refugees including women and children in eastern Zaire in 1996–97.
Rwanda, Dem. Rep. Congo, Tanzania