Dozens kidnapped by rifle-wielding men in northwest Nigeria village - Nigerian army rescues 13 hostages from extremist group - 20 abducted Nigerian medical students freed - Police say 20 abducted Nigerian medical students freed - 20 Nigerian students abducted by gunmen in an ambush in the north - Nigeria gunmen kill 26, kidnap dozens - Nigerian army rescues hundreds of hostages, mostly women and children, from Boko Haram extremists - 9 Nigerian students kidnapped at gunpoint in region's latest school abduction