NEW YORK, Oct. 5.--The Turks and Kurds are waging a holy war of extermination on the Armenians, according to sixteen members of the American Board of Foreign Missions, who arrived from Van, Turkey, on the Swedish steamer Hellig Olav today. Ernest Yarrow, one of the missionaries, told how the Armenian population of Van, numbering 1500, held out against 5000 Kurds and a Turkish company commanded by a German officer from April 20 to May 17, when Russians arrived and relieved the town.