Three soldiers died and one became seriously ill after eating potentially poisonous mushrooms picked near the temple of Preah Vihear, where a border dispute with Thailand continues, military officials said Monday.

The first death took place on July 27, followed by one on July 29 and one on July 30. The fourth soldier remains hospitalized in Siem Reap.

Chea Mon, commander of Division 4, said the men cooked and ate unknown mushrooms in a soup a few days prior to the deaths.

“We tried to cure them, but we couldn’t help, because they ate a lot of poisonous mushrooms,” he said.

The deceased soldiers were identified as Ros Mao, 30, So Rim, 32, and Sing Roeun, 34. Yoeun Be, 30, remains in the hospital.

The soldiers were stationed near Preah Vihear temple, where an ongoing border dispute has meant the mobilization of thousands of soldiers over the past year.

Srey Douk, commander of the armed forces in the Preah Vihear operation, said his soldiers had plenty of food to eat, thanks to donations, and he warned other soldiers against eating unknown mushrooms scavenged from the forest.