Three policemen and a citizen were injured in an armed attack at Okmeydani neighborhood of Istanbul, police said Saturday. The unidentified assailants attacked the riot police unit on duty near the Cemal Kamaci sport complex.The wounded have been carried to hospital, with one officer and the citizen in critical condition, sources said.The police have launched an investigation to find the perpetrators. The attack comes as policemen have been targeted by illegal groups across the country after a suicide attack in southeastern Suruc district killed at least 32 people and injured more than 100.