PHNOM PENH, Jan. 31 (Xinhua) -- Three Cambodian forest protectors had been gunned down in the Keo Seima Wildlife Sanctuary in northeastern Mondulkiri province after they seized chainsaws from illegal loggers, officials confirmed Wednesday.

Keo Sopheak, director of the Environment Department in Mondulkiri province, said a park ranger, a military police officer and a Wildlife Conservation Society employee were attacked late Tuesday afternoon when they patrolled the protected forest.

"They were shot dead when they were returning from their patrol with the chainsaws confiscated from illegal loggers," he told Xinhua, adding that the authorities suspected Cambodian border officials, who collaborated with the illegal loggers, were responsible for the killings.

According to Sopheak, the incident took place in the remote forest, about 4 km from the Cambodia-Vietnam border.

He said as of Wednesday afternoon, perpetrators had not been arrested as an investigation was underway.

In separate condolence letters to the bereaved families, Cambodian Interior Minister Sar Kheng strongly condemned the killings and ordered the authorities to hunt for the perpetrators for prosecution.

In November 2015, two forest protectors -- a police officer and a forest ranger -- were shot dead by illegal loggers in northwestern Preah Vihear province when they cracked down on forest crimes.

Cambodia's forest cover stood at 73 percent in the 1970s, but over-logging has decreased it since then. The report of the Ministry of Environment showed that forest cover was 45.26 percent of the Cambodia's land in 2016.