One of the first thing Chinese government report is that the flood only affect Nepal or seems to guide us to think that way.

There is also a massive censorship campaign on the issue. That is despite the whole Chinese side check point was swept away along with the Nepalese checkpoint.

The current explanation is as follows:

large glacier on the local ice mountain melted, forming a barrier lake. This barrier lake accumulated a large amount of water, with soil and ice blocks forming a natural dam that held it in a depression.

Due to the melting of ice blocks at the dam mouth, soil erosion, or a small earthquake, the dam burst. A mixture of water, mud, and ice rapidly descended 1200 meters from the ice mountain, forming a debris flow flood peak.

After surging for several kilometers, the flood engulfed the river mouth where Jilong Port is located.

Some ice blocks remain at the bottom of the lake. Friends familiar with glaciers can see that these ice blocks have the distinctive blue ice unique to glaciers (due to the pressure from the ice layers causing high ice density, forming blue ice, which will lose its color and turn into ordinary ice blocks after melting for several days).