In 1964, towards the end of the Zanzibar Revolution—which led to the overthrow of the Sultan of Zanzibar and his mainly Arab government by local African revolutionaries—John Okello claimed in radio speeches to have killed or imprisoned tens of thousands of the Sultan's "enemies and stooges",[381] but estimates of the number of deaths vary greatly, from "hundreds" to 20,000. The New York Times and other Western newspapers gave figures of 2–4,000;[382][383] the higher numbers possibly were inflated by Okello's own broadcasts and exaggerated media reports.[381][384][385] The killing of Arab prisoners and their burial in mass graves was documented by an Italian film crew, filming from a helicopter, in Africa Addio.[386] Many Arabs fled to safety in Oman[384] and by Okello's order no Europeans were harmed.[387] The violence did not spread to Pemba.[385] Leo Kuper described the killing of Arabs in Zanzibar as genocide.[388]