Two air conditioner repairmen were killed on Saturday morning when a gas tank exploded as they were repairing a machine at the Pailin Flamingo Casino on the Cambodian-Thai border, according to district police.

Srey Chanra, 25, was killed immediately, while Reav Piseth, 26, sustained serious injuries and died as he was being sent for treatment at a hospital in Chonburi province in Thailand, according to Captain Seng Bunna, deputy chief of Sala Krao district.

Both men worked for the CTS Air Conditioner Company in Phsar Prum village in Pailin province, and had been commissioned by the casino to repair broken units in the building where they died.

“It sounded like an anti-tank [mine] explosion,” Bunna said.

A police investigation indicated the explosion was likely ignited by residual gas left in the air conditioner tank and the heat from welding tools being used in the repair, according to Ouk Kosal, an officer with the Pailin Provincial Police.

He said the victim’s bodies have been returned to their families for funeral services.