The right answer is " the death of the Rwandan president ".
In April 1994, Rwandan President Juvénal Habyarimana (a Hutu) was killed in an attack on the plane in which he was traveling. The next day, the genocide began. Without presenting evidence, Hutu leaders accused the Tutsis of the assassination of the president and urged the population to begin the killing. Hours later, Hutus militias have advanced into villages and towns across the country, killing everything they saw ahead. Control stations were established in the streets. Persons identified as members of the Tutsi minority were summarily executed.