PROVIDENCIALES, Turks and Caicos—A boat was found drifting about a mile off Grand Turk island with 20 dead people on board, including two children, authorities in the Turks and Caicos Islands said Sunday. Officials said investigators had ruled out foul play but were still trying to determine what happened. The identities and origin of the dead were also under investigation. Fishermen spotted the small boat Thursday morning and alerted the marine branch of the Royal Turks and Caicos Islands Police Force, who towed the vessel ashore. The police communications officer, Takara Bain, said in a news release that investigators had discounted foul play and were looking at other possibilities, without giving any specifics. Police Commissioner Trevor Botting said the boat appeared to have come from outside the Caribbean and authorities did not think it had the Turks and Caicos as its destination. “My investigators are working to establish their identities …