On April 12, 1927, Chiang Ka-shek and his Green Gang allies initiated a purge of Communists from the Shanghai Kuomintang and began large-scale killings. Chiang's forces turned machine guns on 100,000 workers who had taken to the streets in labor union demonstrations, killing more than 5,000 people. Throughout April 1927 in Shanghai, more than 12,000 people were killed or disappeared. The man in the picture surveying the slaughter appears to carry a weapon under his arm, and may well have been a 'Green Gang' mobster.