BEIJING, Aug. 27 (Xinhua) -- A massive mudslide that caused casualties and left a large number of people missing at the border port of Gyirong in southwest China's Xizang Autonomous Region was triggered by the collapse of glacier on the Nepalese side at a higher elevation, an expert said.

This photo taken on Aug. 26, 2026 shows an area near Gyirong Port in southwest China's Xizang Autonomous Region. (Photo: Xinhua)

The collapse sent masses of debris rapidly downhill, which swept up moraine material along the way to form a mudslide that struck Gyirong Port before moving downstream toward Nepal, said Guo Zhaocheng, an expert with the Ministry of Natural Resources.

The mudslide struck Gyirong Port in Gyirong County, Xizang, on Wednesday morning. As of 8 a.m. on Thursday, three people had been killed, 558 others remained missing, while two local villagers had been rescued.

The mudslide is estimated to have traveled at about 50 meters per second, an extremely high speed leaving people with little time to react, while the affected area stretched more than 20 kilometers, resulting in severe losses.

Therefore, the disaster prevention and mitigation work on the Qinghai-Xizang Plateau must take a bottom-line and worst-case approach and fully account for such complex conditions, Guo said.