More than 600 workers may be trapped inside mud-filled tunnels near Nepal’s Trishuli River after flooding struck hydropower projects, while rescuers race to reach possible survivors. On Monday, teams tried to access the Trishuli-3 hydropower project by blasting a route through a mountain slope and began pumping air into a tunnel. Nepal’s disaster management authority said the Nepal-Tibet border floods had killed 939 people, with 3,925 missing.

Prime Minister Balendra Shah said 279 people had been rescued from the projects. An international operation led by Chinese and Nepali military personnel includes specialists from India, South Korea and Australia. A rescue team entered a tunnel leading toward one hydropower project on Monday but found no one and withdrew. Relatives of missing workers said oxygen support should have begun sooner and urged faster action.

Australian engineer Arnold Dix said rescuers were struggling even to identify the tunnels’ locations after the devastation, describing the landscape as resembling the moon’s surface. At least 11 completed or under-construction hydropower projects were damaged. Authorities have identified only 4% of nearly 900 recovered bodies, while temporary burials and DNA collection are underway in Chitwan district.