LIMA (AP).- Peruvian authorities say they are struggling to keep outsiders away from a clan of previously isolated Amazon Indians who began appearing on the banks of a jungle river popular with environmental tourists last year. The behavior of the small group of Mashco-Piro Indians has puzzled scientists, who say it may be related to the encroachment of loggers and by low-flying aircraft from nearby natural gas and oil exploration in the southeastern region of the country. Clan members have been blamed for two bow-and-arrow attacks on people near the riverbank in Madre de Dios state where officials say the Indians were first seen last May. One badly wounded a forest ranger in October. The following month, another fatally pierced the heart of a local Matsiguenka Indian, Nicolas “Shaco” Flores, who had long maintained a relationship with the Mashco-Piro. The advocacy group Survival International released