KABUL, Afghanistan The slaughter of students, mostly teenagers, at a tutoring center. The deaths of young athletes in a suicide bombing at a wrestling club. Mothers shot dead with newborns in their arms. These relentless killings of Hazaras, a persecuted minority in Afghanistan, finally proved too much to bear for Zulfiqar Omid, a Hazara leader in the central part of the country. In April, Omid began mobilizing armed men into militias to defend Hazara areas against the Taliban and the Islamic