Gunmen bombed their way into a prison in central Nigeria before opening fire on the wardens and emptying the jail of its estimated 200 inmates, residents and an official said on Thursday. \"Last night around 7:00 pm (1800 GMT), around 20 gunmen attacked the prison. They hurled explosives to blow up the gate of the prison, and engaged the wardens in a shootout,\" said resident Isiaka Yakub, adding the jail was holding some 200 inmates at the time of the attack.