On Wednesday morning, a glacier collapsed above the border between Nepal and Tibet and blocked a river valley in the Himalayas. What came down afterward was a wall of water nearly 30 feet high, tearing through the Rasuwa district along the Trishuli and Bhote Koshi rivers and wiping out communities as far as 62 miles downstream, according to NPR. Two days later, the death toll is still climbing, rescue teams have had to retreat from the worst-hit areas, and more than 1,500 people remain unaccounted for.

At a Glance

  • Two days after a glacier collapse sent a wall of water through the Nepal-Tibet border, rescue crews have had to pull back as a debris-dammed lake threatens to overflow.
  • More than 1,500 people are still missing — over half of them foreign nationals, including dozens of Americans and Indian pilgrims headed to Mount Kailash.
  • On Wednesday morning, a glacier collapsed above the border between Nepal and Tibet and blocked a river valley in the Himalayas.

A death toll nobody can fully pin down yet

Nepali police put the confirmed death toll at 547 as of Friday, while authorities in China — which administers Tibet — reported just 5 dead on their side of the border, per NPR. Other outlets are getting different numbers from the same chaos: ABC News cited a Nepali tally of 579 dead and nearly 1,924 missing in Nepal alone, on top of over 4,451 people injured or rescued and roughly 8,380 police personnel deployed to the region. The gap between those figures isn't really a mystery — it's what happens when phone networks, roads and bridges are gone and every agency is counting under pressure, in the middle of an active rescue.

Why the rescue had to stop

The same landslide-and-glacier event that caused Wednesday's flood also dammed the river with mud, ice and rock, forming a new lake upstream. By Friday, Chinese authorities said that lake had started to overflow, and both Nepali and Chinese rescue teams suspended search operations in the border area as a precaution, satellite imagery reviewed by CNN showed. A second, larger lake was also forming nearby and swelling with fresh rainfall. Nepali police have told residents downstream to stay away from riverbanks until the situation is clearer.

"We don't have a full view about what kind of intensity would come in a second flood."— David Fisher, head of the Red Cross and Red Crescent delegation in Nepal, to NPR

The missing are pilgrims, engineers and soldiers

Nepal and China say more than half of the 1,500-plus people still missing are foreign nationals, and the U.S. State Department has confirmed 90 Americans among them, NPR reported. Many appear to have been Hindu, Buddhist and Jain pilgrims making the trek around Mount Kailash in Tibet, a journey some save for years to take. Among the missing are a retired Queens postal worker and her husband, a retired engineer, who were reportedly at the border crossing when the water hit. Also unaccounted for are Nepali security personnel stationed at the border and engineers who had been working on hydropower projects in the same valley — the area, known as Rasuwa, remains the hardest to reach, with its bridges and roads gone.

What rescue looks like from a helicopter

With roads out, most of the rescue work has fallen to helicopter crews flying in and out of a landscape that, in places, no longer has anywhere to land. One pilot told NPR he'd made around 20 flights and pulled more than 120 people out, including a man who said he'd lost his entire nine-person family to the floodwaters. Aid groups including the Red Cross and Oxfam are now racing to get clean water and basic supplies into areas that helicopters can still reach, even as officials warn that the death count is likely to keep rising in the hardest-hit, least accessible parts of the valley.