PHNOM PENH, Cambodia (AP) — Twenty soldiers were killed and several others injured in an ammunition explosion at a base in the west of Cambodia on Saturday afternoon, Prime Minister Hun Manet said.

Hun Manet said in a Facebook post that he was “deeply shocked” when he received the news of the explosion at the base in Kampong Speu province.

It was not immediately clear what caused the explosion and Hun Manet did not say in his post on Facebook.

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

Pictures from the scene showed a destroyed building still smoldering, and soldiers receiving treatment in a hospital.

Hun Manet, a graduate of the U.S. Military Academy at West Point, was promoted to be a four-star general shortly before he was elected to serve as prime minister, succeeding his autocratic father Hun Sen.