Hutu Rwanda, this led to the "Social revolution" and Hutu violence against Tutsis. Tens of thousands of Tutsis were killed and many others fled to neighboring countries, such as Burundi, Uganda and expanding the Banyamulenge Tutsi ethnic group in the South Kivu region of the Belgian Congo. Later, exiled Tutsis from Burundi invaded Rwanda, prompting Rwanda to close its border with Burundi. In Burundi, a campaign of genocide was conducted against Hutu population in 1972, and an estimated 100,000 Hutus died. In 1993, Burundi's first democratically elected president, Melchior Ndadaye, who was Hutu, was believed to be assassinated by Tutsi officers,
Rwandan genocide president, followed by a command to kill Tutsi. The Hutu population, which had been prepared and armed during the preceding months, and maintained the Rwandan tradition of obedience to authority, carried out the orders without question. In Kigali, the genocide was led by the Presidential Guard, the elite unit of the army. They were assisted by the Interahamwe and Impuzamugambi, who set up road blocks throughout the capital; each person passing the road block was required to show the national identity card, which included ethnicity, and any with Tutsi cards were slaughtered immediately. The militias also initiated searches of houses