The dead man was identified as Mapiyoh Yohnimae, 45, a defence volunteer of Ban Korroramae.
The injuried, assistant village chief Waesama-air Jaru, 45, and civilian Marorsee Makeh, 48, were taken to Yaha hospital.
Pol Lt Thanasak Leelanuch, an investigator at Patae police station in Yaha, said the shooting occurred about 12.45am at house No 88/1 of the defence volunteer on Yaha-Bannang Sata road in tambon Patae.
The three men were sitting chatting in front of the house when two men arrived on a motorcycle. The killer, riding pillion, walked over to them pretending to join in the conversation, then took out a handgun and fired at them. The attackers then fled.
All three victims were rushed to Yaha hospital in critical condition. Mapiyoh, the defence volunteer, was pronounced dead on arrival.
Police blamed separatist militants.