KATHMANDU - Two workers have been rescued alive from a hydropower tunnel in central Nepal, nine days after a catastrophic flood and landslide swept through the Trishuli River corridor, offering fresh hope that other people trapped underground may still be alive.

The two men, identified as mechanical foreman Sanjay Sah and mechanical supervisor Kabir Maharjan, were pulled from a tunnel at the Trishuli 3A Hydropower Project on Friday after rescuers heard voices from inside. Both were airlifted to Kathmandu for medical treatment, according to Kathmandu Post.

The breakthrough came after rescue teams from the Nepali Army and Armed Police Force entered the tunnel and established communication with people believed to be trapped inside. Rescuers reportedly called out to those underground and received a response, prompting an intensified operation.

Officials and rescue workers believe hundreds of hydropower workers may still be unaccounted for across several projects affected by the disaster. Around 900 workers were reported missing from six hydropower projects along the Trishuli River, with many believed to be trapped inside tunnels.

The rescue came as Nepal continued to deal with one of its worst disasters in recent years.

According to figures compiled by Nepal’s National Disaster Risk Reduction and Management Authority, 1,252 people had died and at least 4,216 remained unaccounted for as of Thursday. The hardest-hit districts included Chitwan, Nawalparasi East, Nawalparasi West and Nuwakot.

The disaster was triggered on Aug. 26 when a massive surge of water, ice, rock and mud swept through valleys in northern and central Nepal, devastating communities, roads, bridges and hydropower facilities.

The disaster also affected neighboring China. Chinese authorities have reported 21 deaths and hundreds of people missing on the Tibetan side of the border.

The survival of Sah and Maharjan has renewed hopes for dozens of other people believed to be trapped underground.

Tunnel experts assisting the rescue effort have warned that silence from underground does not necessarily mean people have died. Underground structures can provide protection from extreme weather and may contain pockets of breathable air and relatively safe spaces.

International tunnel expert Arnold Dix, who has been advising the Nepal rescue operation, cited previous disasters in which people survived for days or even weeks underground. He said rescue teams should continue treating the operation as a rescue rather than a recovery mission.

Rescue teams are continuing to clear mud, water and huge rocks from damaged tunnels while using heavy equipment and other techniques to reach potentially isolated workers.

The rescue of the two men has transformed an increasingly desperate search into a renewed effort to locate other possible survivors — nine days after the disaster devastated the Trishuli River valley.