The death toll from devastating Himalayan glacial floods crossed the grim 1,000 mark on Tuesday, as Chinese and Nepali teams searched for survivors including dozens feared trapped in hydropower tunnels.

Nearly 4,500 people are missing after the gigantic wave of freezing water, rocks and debris triggered by a high-altitude glacial collapse roared downstream on Wednesday, wiping out entire settlements and carving a path of destruction across Nepal.

Nepali rescue teams are digging, drilling and blasting through debris in a desperate race against time to free around 100 hydropower workers believed trapped in multiple tunnels.

So far, rescuers have recovered only bodies from tunnels blocked by sludge, and hopes of finding survivors are fading.

Excavators worked into the night on Tuesday, but an army update noted that “a large amount of water started flowing” into a hole they were digging, forcing them to start a new opening.