During the 1936–1941 Italian occupation, atrocities also occurred; in the February 1937 Yekatit 12 massacres as many as 30,000 Ethiopians may have been killed and many more imprisoned as a reprisal for the attempted assassination of Viceroy Rodolfo Graziani. A 2017 study estimated that 19,200 were killed - a fifth of the population of Addis Ababa. The Ethiopian Orthodox Tewahedo Church was especially singled out. Thousands of Ethiopians also died in concentration camps such as Danane and Nocra.