The events around the genocide memorial kknown locally as Kwibuka25, began in the capital Kigali on Sunday with President Paul Kagame, as well as the Prime Ministers of Belgium and Ethiopia in attendance.
Chad’s Idriss Déby, Congo’s Denis Sassou Nguesso, Djibouti's Ismaïl Omar Guelleh and Niger’s Mouhamadou Issoufou are the four presidents also present at the ceremony.
Ten presidents were announced for the occasion by the organizers.
Belgian Prime Minister Charles Michel, his Ethiopian counterpart, Abiy Ahmed, the Deputy Governor of Canada and several other foreign delegations are also present at the commemoration which began on Sunday morning at the site of the Genocide Memorial in Gisozi.
The memorial is the burial site for more than 250,000 people slaughtered during the 1994 genocide.
While there, the heads of state lit the so-called "torch of memory" in rememberance of an estimated 800,000 people thought to have been killed during the 100-day genocide.