Between 100,000 and two million Indonesians were killed in the mass killings that followed. The victims included non-Communists who were slain because of mistaken identity or guilt by association. Although a lack of information makes it impossible to pinpoint an exact casualty figure, many scholars today suggest that the figure is at least 500,000. According to a CIA study of the events in Indonesia, "In terms of the numbers killed the anti-PKI massacres in Indonesia rank as one of the worst mass murders of the 20th century".