Police in the northern province of Bac Ninh on Wednesday launched a criminal investigation into a local scrap dealer for illegally stockpiling and trading military weapons.

Nguyen Van Tien, 54, is facing criminal charges after his warehouse in Quan Do Village, Yen Phong District exploded, killing two and leveling a part of the village on Wednesday morning.

Under police interrogation, Tien claimed he had bought about 7 tons of old 12.7mm and 14.5mm bullets since December 2016 to recycle. The bullets were stored at the warehouse at the time of the explosion, but Tien claimed he did not know why they exploded.

"We are still trying to determine the cause [of the explosion] and whether there are accomplices. All confiscated warheads will be handed over to the military to be dealt with," the head of Bac Ninh police said.

The site of the explosion in Quan Do Village, Bac Ninh Province on Wednesday morning. Photo by VnExpress.

The explosion, which occured at around 4:30 a.m., killed two children and injured at least six others. It also destroyed seven houses, damaged about a dozen more and left a deep crater at the site.

Authorities' initial evaluation estimates that those within a radius of up to 5 kilometers (3.1 miles) from the site have been affected.

According to Nguyen Van Loi, a local villager and one of the blast's victims, Quan Do Village has a long tradition of scrap dealing. He claimed that many families in the village also collect and sell old munition to recyclers.

"My entire village works in this line of business so the explosion this morning is just an unavoidable accident," Loi said.

Tien is a well-known scrap dealer in the village, according to villager Nghiem Thi Thao. Another explosion had also occured at Tien's house nearly 10 years ago, killing one person, she said. Since then the house has only been used as a warehouse and no one lives there anymore.

Decades after the Vietnam War ended, unexploded ordnance still threatens a fifth of the country’s land mass and explosions occur frequently, killing more than 1,500 people every year and maiming and injuring 2,200 more, according to official data.

According to the United Nations, 104,000 Vietnamese people have been killed by bombs, land mines and artillery shells since the end of the war in 1975.

Many people from poor rural areas are killed by inadvertently triggering the devices, while others die trying to cut them open to resell the explosives and scrap metal. In August, six members of a family in the central province of Khanh Hoa died in one such blast.