An artificial earthquake caused by a North Korean nuclear test in September reportedly caused buildings to collapse and killed scores of people, including schoolchildren, South Korean media reported this week.

On Sept. 3, North Korea conducted its sixth nuclear test, successfully detonating a hydrogen bomb — one that could fit onto an intercontinental missile (ICBM).

The blast produced two shallow earthquakes in the Punggye-ri region, where North Korea's nuclear test facility is located, U.S. and Chinese government seismologists reported at the time. Authorities in Japan, South Korea and numerous nongovernment experts in the United States confirmed that the earthquakes were likely the result of a nuclear test.

North Koreans watch a news report showing North Ko FILE - North Koreans watch a news report showing North Korea's nuclear test in Pyongyang, North Korea, Sept. 3, 2017. (Kyodo/via Reuters) FILE - North Koreans watch a news report showing North Korea's nuclear test in Pyongyang, North Korea, Sept. 3, 2017. (Kyodo/via Reuters)

Nearby village badly damaged

An unnamed source, who recently visited a village about 8 kilometers from Punggye-ri, described the damage to the South and North Development (SAND), a research institute that works with defectors from the North, according to the South Korean newspaper Chosun Ilbo.

The source said houses and a school collapsed in the village of Sindong-ri and that dozens of people were killed and injured, the paper reported.

"September 3 was a Sunday, but some 150 students were waiting in their classrooms to do some work," the source said, according to Chosun Ilbo. "Casualties occurred when half of the school building crumbled."

After the detonation in September, the first earthquake was a 6.3-magnitude tremor that was consistent with the detonation of a 1-megaton hydrogen bomb, according to experts. Five minutes later, the same seismologists detected a magnitude-4.6 earthquake, which indicated the likely collapse of a tunnel in which the nuclear device was placed.

In October, Japanese television channel Asahi TV reported the collapse of an underground tunnel at the Punggye-ri nuclear facility, saying it likely caused the death of about 200 people.

Harvest delays repairs

In the village affected by the earthquakes, the source told SAND that the damage to buildings had yet to be repaired because farmers were busy with the harvest.

"Farmers couldn't even think of repairing the damage because they're busy harvesting crops even though three months have passed since their houses were destroyed," the source said, as reported by Chosun Ilbo. "Displaced farmers are staying in temporary shelters or living with neighbors whose houses sustained less damage."

The Washington Post reported in October that experts feared Mount Mantap, the 2,195-meter-high peak under which the tests are conducted, was suffering from "tired mountain syndrome," and could collapse, releasing radiation from the nuclear explosions.

North Korean leader Kim Jong Un has prioritized developing a nuclear-tipped ICBM that could hit mainland U.S. Before the Sept. 3 nuclear test, Pyongyang had conducted 21 missile launches this year, including two ICBM tests in July.

The rogue nation last launched a missile Sept. 15, from the Sunan district in Pyongyang. It flew over the northern Japanese island of Hokkaido and landed in the sea.

North Korea conducted its first nuclear test Oct. 9, 2006.

Brian Padden in Seoul contributed to this report.