TOKYO, June 9, (AP): An explosion at a storage site for unexploded ordnances at a US military base on Japan's southern island of Okinawa injured four Japanese soldiers, though the injuries are not life threatening, officials said Monday. The four soldiers sustained finger injuries while working at a facility that belongs to Okinawa prefecture and temporarily stores unexploded ordnance, mostly from wartime and found on the island, local officials said.

One of the harshest battles of World War II was fought on Okinawa. Prefectural officials said the injuries were not life threatening, but no other details were immediately known. The US Air Force said in a statement that the explosion occurred inside the facility managed by the Okinawa prefectural government at Kadena Air Base's munitions storage area.

It said no US servicemembers were involved in the incident. The Self Defense Force's joint staff said one of the ordnances suddenly exploded when the soldiers were inspecting it at the facility. The blast occurred when the soldiers were trying to remove rust to examine details of the unexploded ordnance, NHK television reported. The SDF said they are trying to confirm what caused the accident.

Hundreds of tons of unexploded wartime bombs, many of them dropped by the US military, remain buried around Japan and are sometimes dug up at construction sites and elsewhere. Many of them are still found on Okinawa, where about 1,856 tons of unexploded US bombs are believed to remain. In October, an unexploded wartime US bomb exploded at a commercial airport in southern Japan, causing a large crater and suspending dozens of flights.