Kathmandu— A flash flood triggered by a glacier collapse in the Himalayas on Wednesday has claimed over 470 lives and left nearly 1,500 missing across Nepal and Tibet. Rescue efforts were paused Friday as a “barrier lake” – formed when debris blocked a river – began to overflow, threatening downstream communities with another surge of water and hindering the delivery of vital relief supplies.

Rising Lake Threatens Further Disaster

The barrier lake, created by mud and debris carried down a steep valley during Wednesday’s flood, is rapidly expanding. Chinese authorities reported Friday that its volume had increased to over 2.5 million cubic metres from an estimated 1.5 to 2 million cubic meters the previous day. Nepalese officials confirmed the lake began breaching its banks, prompting a temporary halt to search operations for missing persons. Narendra Pariyar, top administrator in Nepal’s Rasuwa district, stated that rising river levels were visible, though the exact height of any surge remains unclear.

Glacier Collapse and Initial Impact

The disaster began with the collapse of a glacier, unleashing a torrent of ice, water, rock, and mud down Himalayan river valleys. Entire villages were buried, and critical infrastructure including roads, bridges, and hydropower plants were destroyed. The initial flood caused widespread devastation in Nepal’s Rasuwa district, bordering Tibet, where residents scrambled to higher ground as river levels rose. Approximately 90,000 people are estimated to have been affected by the disaster, according to the Red Cross.

Rescue and Relief Efforts Hampered

Despite the escalating risks, rescue teams from both Nepal and China had initially mobilized to search for survivors. However, the growing threat of the barrier lake forced Chinese teams to withdraw to safe ground, as reported by CCTV. Approximately 800 people have been rescued by helicopter and 700 by land, with airlifts delivering essential aid. David Fisher, head of delegation for the International Federation of Red Cross and Red Crescent Societies in Nepal, expressed concern about a potential secondary flood and noted that relief supply deliveries were being blocked by the overflowing lake.

Government Response and Missing Persons

The Nepalese prime minister’s office reported 469 confirmed deaths with 977 people still missing as of Friday. Chinese authorities have confirmed at least five deaths in Tibet, with 558 individuals unaccounted for. China has deployed around 500 military and paramilitary personnel, along with Premier Li Qiang to oversee operations. Nepal has mobilized 30,000 security personnel to search remote valleys cut off by the disaster.

Authorities continue to monitor the barrier lake closely, assessing the risk of further overflows and working to deliver aid to affected communities as conditions allow. The number of missing is expected to rise as rescue efforts resume when it is safe to do so.

(With inputs from Al Jazeera)

Originally published on abcnews.com.np.