An Australian man and his British colleague working to map unexploded bombs have been killed in an explosion at their home in Honiara, the capital of Solomon Islands.

Australian Trent Lee and Briton Stephen “Luke” Atkinson died when an unexploded ordnance is believed to have detonated shortly after 7.30pm on Sunday.

The blast, inside the men’s rented accommodation in Tasahe, in the west of the city, was felt more than five kilometres away: cries for help from inside brought rescuers and emergency services to the building.

The two men were employees of the NGO Norwegian People’s Aid (NPA), which maps unexploded ordnance across Solomon Islands, working alongside the police bomb disposal unit.

Solomon Islands was a key second world war battleground and its islands remain littered with thousands of bombs and unexploded ordnance more than seven decades later.

Workers are in the capital, on the island of Guadalcanal, clearing sites of bombs ahead of the 2023 Pacific Games.

The two men were reached by rescuers alive but were declared dead at hospital.

Witnesses told the Guardian “this whole neighbourhood felt the explosion … we knew straight away it was a bomb”.

“People now want to know why there was a bomb in a residential neighbourhood.” Tasahe is an upmarket suburb in Honiara’s west, home to many of the city’s expatriate community, diplomatic staff, and ambassadors.

Lee had written previously about the dangers he faced identifying and defusing decades-old unexploded bombs. Posting a picture of a US naval round online last month, he wrote: “pretty much the most dangerous WW2 ammunition we find … it’s cocked and ready to fire … one bump and it’s all over.”

Deputy secretary general of NPA, Per Nergaard, said the explosion was “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.”

NPA’s activities in Solomon Islands have been suspended, and the organisation is assisting police with their investigations.

Inspector Clifford Tunuki from the Royal Solomon Islands police force said police had secured the scene and forensic investigators would determine what had caused the blast.

Investigators will seek to determine why explosives were present at a block of residential flats, which also serve as the NPA’s project office.

“We call on members of the public in the Tasahe area of West Honiara to please stay well away from the area of the incident and allow … officers to do their work as we investigate this tragic incident,” Tunuki said.

Tunuki said police worked alongside NPA in locating and disposing of unexploded ordnance, but there were no police present when the explosion occurred.

“The survey team goes out to confirm the location of the unexploded ordnance following reports from the communities and the information is relayed to us. We determine what to do with the unexploded ordnance after the survey has located them,” Tunuki said.

“On behalf of the Royal Solomon Islands police force I wish to convey my sincere condolences to the family and relatives of those two foreign nationals who died in this tragic incident.”