Gunmen suspected of belonging to a radical Islamist sect attacked a village in northeast Nigeria, tying up men, women and children before slitting their throats and killing at least 15, witnesses said Saturday. The assault took place Friday morning in Musari, a village on the outskirts of Maiduguri, the city where the sect known as Boko Haram first began its campaign of shootings and car bombings against Nigeria’s weak central government.