Japanese media is reporting that 200 North Koreans died in a tunnel collapse at the nation’s nuclear test site.
The catastrophe comes after the September nuclear weapon testing that reports say shook the mountain, causing it to become unstable.
Further extensive damage is possible if the testing site has been completely compromised, since the radioactive materials could spread throughout the region.
Japan’s TV Asahi announced that this was North Korea’s most powerful underground nuclear test. The collapse occurred in Punggye-ri, the country’s northeast territory.
Experts believe the nuclear device North Korea detonated under a mountain early in September was a hydrogen bomb. They assess the bomb to have been about ten times more powerful than the first atomic bombs dropped on Japan at the close of World War II.
Since that explosion, satellite imagery has shown the mountain above the test site has undergone a series of landslides, and substantial aftershocks, widely thought to be effects from the blast.
TV Asahi says that North Korean sources told them a tunnel collapsed on 100 workers. When an additional 100 went in to rescue them, they also died under the fragile mountain.
The tunnels in and out of the test site were reported to have had previous damaged. It is unknown if the workers may have been clearing or repairing the tunnels in order to continue nuclear testing.