Japanese media has released details into an apparent tunnel collapse in North Korea’s nuclear test site that is believed to have killed as many as 200 people.

In a report made on Tuesday, Japanese TV Asahi claimed that some 100 people were trapped or killed in an initial collapse that occurred days after North Korea’s sixth nuclear test in September.  The test was believed to have been North Korea’s first successful detonation of a two-stage thermonuclear device, commonly referred to as a hydrogen bomb, and was significantly more powerful than previous tests conducted by Kim’s regime.

More than 100 more people were sent in to conduct rescue and recovery operations within the tunnel when a second collapse enveloped the rescue effort, bringing the reported death toll up to as many as 200 people.

Rumors have swirled about the stability of North Korea’s Punggye-ri nuclear test site in recent weeks, as a series of tremors and landslides that registered on seismographs outside the reclusive state following the September 3rd detonation led some Chinese scientists to speculate that the mountain range over the underground facility was suffering from “tired mountain syndrome.”