That year Diagne was sent to Rwanda as part of an Organisation of African Unity military observer team tasked with monitoring the Rwandan Civil War, a conflict fought between the Hutu-dominated government and the Tutsi-led Rwanda Patriotic Front (RPF). Later he was assigned to the United Nations Assistance Mission for Rwanda (UNAMIR), a UN peacekeeping force meant to oversee the implementation of the Arusha Accords—a peace agreement designed to end the war. In April 1994 the President of Rwanda was killed. Hutu extremists initiated the Rwandan genocide, targeting members of the Tutsi ethnic minority. They murdered moderate Hutu Prime Minister Agathe Uwilingiyimana, and Diagne rescued her children and secured them safe passage out of the country. He then undertook numerous missions on his own around Kigali in violation of the UN's rules of engagement, hiding Tutsis in his car and evacuating them to UN installations. He also protected some Hutus and worked to safeguard the Senegalese expatriate community. Various estimates exist for the number of lives Diagne saved, ranging as high as over 1,000.