TOKYO (AP) — An unexploded U.S. bomb from World War II that had been buried at a Japanese airport exploded Wednesday, causing a large crater in a taxiway and the cancellation of more than 80 flights, Japanese officials said.

No one was hurt, and there were no aircraft nearby when the bomb exploded at Miyazaki Airport in southwestern Japan, Land and Transport Ministry officials said.

An investigation by the Self-Defense Forces and police confirmed the explosion was caused by a 500-pound U.S. bomb and there was no further danger. Officials were determining what caused its sudden detonation.