Unexploded U.S. World War II bombs that were buried in an airport in Japan exploded on Wednesday. The explosion caused a large crater and forced the cancellation of over 80 flights, but there were no injuries reported by Japanese officials.

Officials from the Land and Transport Ministry said that there was no aircraft in the vicinity when the bomb exploded at Miyazaki Airport, southwest Japan.

An investigation by the Self-Defense Forces (SDF) and the police revealed that the explosion had been caused by a 500-pound U.S.-made bomb. There was no other danger, officials said. They are trying to determine what caused the bomb’s sudden detonation.

Video taken by an aviation school nearby showed asphalt pieces being similarly thrown into the air to a fountain. Japanese television broadcasted videos showing a crater on the taxiway that was reportedly 7 yards wide and 3 feet deep.

Yoshimasa Hayashi, Chief Cabinet Secretary of Japan, said that more than 80 flights were canceled. The airport hopes to resume normal operations by Thursday morning.

Hayashi stated that there was no danger of a second blast. Police and firefighters were currently inspecting the scene.

According to AFP, a fire department received a call at 7:59 am from an airport indicating that smoke was involved in the incident.

Miyazaki Airport, built in 1943, was a former Imperial Japanese Navy training area from which kamikaze fighter pilots launched suicide attacks.

Defense Ministry officials confirmed that several unexploded U.S. bombs from World War II were found in the area.

In 2009 and 2011, it was reported that the United States dropped other unexploded ordinances at a construction site nearby.

Unexploded bombs weighing hundreds of tons from World War II are still buried in Japan. They can be dug up on construction sites.

Reuters reported that the Self-Defense Force had destroyed 2,348 bombs weighing a total of 41 tons during the fiscal year 2023.

Authorities describe the explosion of a World War II Bomb found in England as “unplanned”.