Hundreds believed trapped in hydropower tunnels after Nepal flooding

Caution: The video for the following story may be considered disturbing.

A desperate race is on to save hundreds of people believed to be buried deep inside hydropower stations on the Nepal-China border.

More than 900 workers at a dozen sites covered in thick mud and debris are thought to be trapped inside.

In total, more than 4,400 people are missing and more than 950 are dead after devastating flooding swept through the Himalayas last week.

Rescue workers from Nepal, India and China are stepping up efforts to try and reach the hundreds believed to be trapped in rooms and tunnels in the depths of the mountains.

About 500 of the missing are thought to be inside the mud-blocked hydropower project tunnels, which are built for controlling the flow of water.

Rescue teams are using controlled blasts and excavators to look for any survivors, who some experts believe may have access to oxygen.

“The only one hope left is he’s still inside the tunnel and he’s alive,” says Arbindra Khadka, whose brother is missing.

But hope fades as the hours tick by.

Several bodies have been discovered in the tunnels and despite an initial call for help from some inside, rescue teams have found no signs of life since.

“Nothing yet. So we are trying our best to get in through,” says an unnamed Nepali rescuer.

The landscape above is marked with the destruction wrought by the powerful flash flooding, caused by a glacial collapse high in the Himalayan mountains last Wednesday.

WATCH MORE: Rescue operations in Nepal continue as flooding kills nearly 580, over 2,500 people still missing

The rockfall was so extreme it registered as a magnitude 5.2 seismic event.

The mudslide washed away buildings, bridges and people, including at a border crossing between Nepal and China.

Hundreds of unidentified bodies that washed down rivers have been retrieved and buried in mass graves.

The locations marked and DNA collected so they can be exhumed later if identified through genetic testing.

Caught up in this catastrophe are the families.

Some looking for their loved ones – combing through photos of the missing and dead – and others, mourning the victims.

Left with the grim task of organizing the cremation of those who have been found, but are already gone.

Foreign Affairs Minister and Oakville MP Anita Anand released an update revising the number of Canadians unaccounted for in the area.

The minister says 30 are missing, down from 31 previously because one person was not actually in the region.

Ottawa has sent ten trained officials to Nepal including a member of the RCMP, who are all working to help locate those unaccounted for Canadians.

READ MORE: Death toll surpasses 500 in Nepal floods, 30 Canadians missing