Italy's alpine rescue service says a 55-year-old American tourist has died after being taken ill during an excursion on on the southern side of Mount Etna. Rescuers said the cause of his illness was unknown, but warned against the risk from high temperatures coupled with humidity that may prove dangerous for tourists who usually have no specific preparation for such excursions. After being alerted on Thursday afternoon, the alpine rescue team and an air ambulance reached the man in a remote area. Attempts to revive him were unsuccessful. Etna, the highest active volcano in Europe, has seen a significant increase in activity over the past week.