Blast reported near U.S. base in Japan.

TOKYO - A U.S. Army official confirmed a small explosion outside an American base south of Tokyo, but there were no reports of injuries or damage. An explosion was heard near the base late Monday, and police suspected an attempted attack on the base, Kyodo News agency reported.

The blast was in the area of the U.S. Army’s Camp Zama, Kyodo said. The report did not say whether there were injuries or damage.

Police found parts of “launch pad” near the base, Kyodo said, and investigators suspected a “guerrilla attack.”