In this image taken from video footage run on Thursday, Oct 18, 2018 by China's CCTV via AP Video, a military helicopter deploys after a landslide formed a barrier lake on Yarlung Tsangpo in Tibet in western China. Thousands of people have been evacuated following a landslide in Tibet that blocked the flow of one of the region's key rivers, China's emergency services said Thursday. (CCTV via AP Video)