In fresh incidents of elephant depredation, as many as 15 houses were destroyed and two cows killed by a marauding herd in Katonibari Tea Estate and Gangapar areas near Gibbon Wildlife Sanctuary last night. According to sources, the jumbos entered the labour lines in the tea estate by crossing over the road. There are, however, no reports of any human casualty. The elephants, which number 22, are permanent residents of the wildlife sanctuary which is spread over an area of 19 square kilometres. Their movement towards Naga Hills, which once used to be their habitat, has been resisted by the Nagas who practise shifting cultivation in the hilly terraces, the sources pointed out.