CHBAR MON, Cambodia (AP) — Security was tight around a military base in southwestern Cambodia on Sunday, a day after a huge explosion there killed 20 soldiers, wounded others and damaged nearby houses.

Guards sought to keep media away from the site in Kompong Speu province.

Hun Manet said in a Facebook post on Saturday that he was “deeply shocked” when he received the news of the blast in the province's Chbar Mon district. It was not immediately clear what caused it.

A villager living nearby told The Associated Press on Sunday that he trembled after hearing the blast because he had never before experienced such a loud explosion.

“When the explosion happened, I was fixing my house with some construction workers,” said Chim Sothea. “Suddenly there was a loud explosion, causing my house to shake and breaking tiles on my roof. They fell down but luckily they didn’t fall inside the house.”

Images from the scene showed several badly damaged buildings on the base, at least one with its roof blown off, and soldiers receiving treatment in a hospital. Other photos showed nearby houses with holes in their roofs.

Four buildings — three for storage and one work facility — were destroyed and several military vehicles damaged, Col. Youeng Sokhon, an army officer at the site, said in a brief report to army chief Gen. Mao Sophan, posted on social media. He added that 25 villagers’ homes were damaged as well. Photos of the base showed the damaged structures in a large field, apparently with no civilian structures close by.

Another villager, who asked to be named only as Sophal, told AP he had heard a sharp sound, and when he saw smoke rising from the direction of the army base, he realized it was an explosion at the arms depot. He then ran back to his house from the small shop where he sells food and drink to shelter inside with his wife and two children.

He said the military immediately closed the road to the base and “villagers were in a panic, seeking a safe place.” He then moved his family to his parent’s home, farther away from the base. When he returned to his own house hours later, he found it undamaged but other villagers’ houses had broken windows, doors and roofs, he said.

Cambodia, like many countries in the region, has been suffering from an extended heat wave, and the province where the blast took place registered a high of 39 C (102 F) on Saturday. While high temperatures normally can’t detonate ammunition, they can degrade the stability of explosives over a period of time, with the risk that a single small explosion can set off a fire and a chain reaction.

Kiripost, an online English language news service, quoted villager Pheng Kimneang as saying a major explosion occurred at about 2:30 p.m., followed by smaller blasts for about another hour.

In March 2005, a nighttime blast at an arms depot in the northwestern provincial town of Battambang triggered an hourslong spray of shells and bullets, killing at least six people and panicking local residents.

A 2014 report by the Swiss-based group Small Arms Survey highlighted the dangers of poorly stored or mishandled munitions, calling it a “global problem.” It noted that from 2013 through 2019 there were more than 500 incidents involving unplanned explosions at munitions sites.

“A single unplanned explosion at a munitions site can claim dozens of lives, injure hundreds of people, and displace thousands,” it said. “The damage to infrastructure can be extensive, covering many square kilometers. In addition, the loss of economic activity can exceed tens of millions of dollars and have long-term ramifications for livelihoods and the environment.”

Hun Manet offered condolences to the soldiers’ families and promised the government would pay for their funerals and provide compensation both to those killed and those wounded.

A graduate of the U.S. Military Academy at West Point, he was army commander before he was elected last year to serve as prime minister, succeeding his father Hun Sen, who led Cambodia for 38 years before stepping down.

U.S. Ambassador W. Patrick Murphy, in a post on the social platform X, extended condolences to the families of the soldiers affected by the explosion.