Two aid workers are dead after a World War II-era ordinance they were working on exploded in the Solomon Islands.

The two men, one British and one Australian, were killed by the blast on Sunday in the house they shared. They were part of the humanitarian group Norwegian People’s Aid, which is working with local authorities to track and chart unexploded ordinances that have plagued the Solomon Islands since the end of World War II, according to the New York Times.

In a statement, NPA Deputy Secretary-General Per Nergaard identified the two men as Stephen “Luke” Atkinson, 57, and 40-year-old Trent Lee. Nergaard called the explosion a “tragic accident.”

“So far, we know that there has been an explosion with fatal consequences. Our main priority now is to offer assistance to relatives and colleagues and to clarify what has happened,” Nergaard said. “NPA's activities on Solomon Islands have temporarily been put on hold, and NPA is working together with the Royal Solomon Islands Police Force, which is investigating the incident.”

Unexploded ordinances are of huge concern for residents of the Solomon Islands, a country of about 650,000 people located northeast of Australia. During World War II, U.S. and Allied forces battled Japanese troops in the Solomon Islands for years, resulting in the island nation being littered with aging explosives.

While no data exists on how many people have been wounded or killed by World War II-era bombs in the Solomon Islands, advocacy groups have estimated that about 20 people are killed or injured by the explosives each year.