In May 1963 nine unarmed Buddhist protesters in the city of Hué were killed with guns and hand grenades by South Vietnamese Army and security forces of the government of Ngô Đình Diệm, a Roman Catholic.

The Buddhists had been protesting a government ban on flying the Buddhist flag on the day commemorating the birth of Gautama Buddha. Diệm denied governmental responsibility for the incident and blamed the Việt Cộng.

The Buddhist demonstrations continued throughout spring and summer and culminated in June when a Buddhist monk publicly lit himself on fire. The photograph of the event made news around the world.

Source: Wikipedia

List of political self-immolations - Wikipedia