ITOMAN, Okinawa — What’s believed to have been an undetonated World War II bomb exploded at a construction site in southern Okinawa on Wednesday, seriously injuring one person.

An Okinawa police spokesman said 25-year-old Jun Kohagura was operating an excavating machine when he was thrown by an explosion at 8:20 a.m. The device was buried about a meter underground, he said.

The explosion left a crater 15 feet wide and about five feet deep, he said.

The excavator was working on a project to install a new water main less than 30 yards from a home for seniors, the police spokesman said. The blast shattered windows and sent chunks of asphalt and concrete flying.

"We believe the bomb exploded by coming into contact with the power-shovel machine," the spokesman said.

The construction worker was found conscious and was rushed to a nearby hospital, where he was treated for excessive bleeding to his face and chest, said Yoshinori Kinjo, a spokesman for the Itoman Fire Department. He was listed in stable condition Wednesday afternoon.

The blast could be heard and felt at the Itoman City Hall, more than a mile away from the site, said Yoshimitsu Kinjo, assistant chief of the city’s waterworks division.

"When I rushed to the site, I saw safety fences, dirt and even stones were blown away, and the windows of a nearby building were shattered," he said.

About 100 windows in 60 rooms at the seniors home were blown out, said Masafumi Tamaki, a spokesman for the facility, which has about 160 residents.

Tamaki said one resident had a minor cut on his ankle and was treated at the facility. He said almost all the residents were in the cafeteria for breakfast.

"It gives me the creeps thinking how disastrous this could have been had the residents been in their rooms at the time," Tamaki said.

Discovering unexploded military ordnance is common on Okinawa, where Japan’s Ground Self-Defense Force has disposed of more than 1,500 tons of unexploded ordnance from the Battle of Okinawa in 1945.

Prior to Wednesday’s blast, the latest find was in December, when a Naha-based disposal unit recovered mortar shells, bullets and land mines from 13 construction sites and farms in Urasoe, Nishihara and Yonabaru, said JGSDF spokesman Masaru Kaneko.

He said the JGSDF has conducted more than 30,000 bomb disposal operations since the island reverted from U.S. military to Japanese control in 1972. The bomb disposal units removed and destroyed more than 1.38 million separate pieces, or 1,578 tons of unexploded ordnance, during that time.

During a December interview, Kaneko told Stars and Stripes that bomb disposal units annually recover an average of about 30 tons of unexploded ordnance dating from the ferocious 83-day battle known locally as "The Typhoon of Steel." He estimated that 2,500 more tons of unexploded ordnance remain buried in the prefecture, and it could take 80 years or more to find and dispose of it all.

Most unexploded bombs are found at construction sites on southern Okinawa, where much of the battle took place. There have been few injuries, Japanese officials have reported.

Lt. Col. Akinori Nagai, chief of the 101st Explosive Ordnance Disposal Unit at the 1st Combined Brigade of the JGSDF’s base in Naha, said 30,000 disposal operations have been conducted without a single mishap.

And it’s not just Okinawa that faces the constant threat of unexploded World War II ordnance.

Last May some 16,000 people were evacuated in Tokyo as Japanese troops removed a one-ton bomb found buried at a construction site in the residential area of Chofu.

Previous incidents

Prior to Wednesday, seven Okinawans had been killed and 47 injured on Okinawa since 1974 in incidents involving ordnance dropped during the Battle of Okinawa in 1945.

1974 – In March, four people, including a child, were killed and 34 were injured when a bomb exploded during work on a sewer line at St. Matthews Kindergarten in Naha.

1975 – In May, two elementary school children were injured when a bomb exploded at the seawall in Chinen.

1975 – In September, one person was killed on Irabu Island when he cut into an unexploded bomb found on his property.

1976 – In July, four children were injured when they threw stones at an unexploded bomb in Urasoe.

1978 – In July, two firefighters were injured in an incident in Haebaru.

1978 – In April, one person was injured when a bomb was set off in a brush fire.

1984 – In November, one child was injured when an unexploded bomb was thrown into a fire at an elementary school in Kadena Town.

1987 – In January, one person was killed while disassembling a piece of WWII ordnance in Naha.

1989 – In April, one person was killed when his lawnmower struck a bomb in Naha.

1991 – In December, one person was injured while burning construction materials in Itoman.

1997 – In November, one person was injured while cutting grass in Kadena Town.

2001 – In June, one person was injured at a construction site explosion involving WWII ordnance in Nishihara.

From The Okinawa Prefectural Crisis Management Department

Sign Up for Daily Headlines

Sign up to receive a daily email of today's top military news stories from Stars and Stripes and top news outlets from around the world.

Sign Up Now