An American World War II-era bomb buried beneath a busy Japanese airport exploded Wednesday, cratering a busy taxiway and forcing the cancellation of dozens of flights, officials said. 

According to Land and Transport Ministry officials, there were no aircraft nearby and no injuries were reported when the bomb exploded at Miyazaki Airport in southwestern Japan.

Investigators determined that the explosion came from a WWII-era 500-pound bomb, though it’s not clear what caused the sudden detonation. 

Miyazaki Airport was built in 1943 as a former Imperial Japanese Navy flight training field from which some kamikaze pilots took off on suicide attack missions.

A video recorded by a nearby aviation school showed the blast spewing pieces of asphalt into the air like a fountain. Videos broadcast on Japanese TV showed a crater in the taxiway roughly 20 feet in diameter and around 3 feet deep.

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Chief Cabinet Secretary Yoshimasa Hayashi said more than 80 flights were canceled at the international airport, which hopes to resume operations Thursday morning.

This photo taken from a Kyodo News helicopter shows part of a damaged taxiway at Miyazaki Airport in southwestern Japan, Wednesday, after an explosion was reported. (Kyodo News via AP)

A number of unexploded bombs dropped by the U.S. military during WWII have been unearthed in the area, Defense Ministry officials said.

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Hundreds of tons of unexploded bombs from the war remain buried around Japan, and are sometimes dug up at construction sites.

The Associated Press contributed to this report.