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.”