Sulaimi bin Mat Ali, 54, died at the Sungai Kolok Hospital after the 8:30pm shooting at his car workshop on Soi Pracha Ruamjai off Pracha Uthit 2 Road in Ban Sarayor village in Tambon Pasemus.
Sulaimi was shot three times.
Muhumad Shahrul Aima Aziz, 19, was shot in his right arm.
Police said the two Malaysians were having dinner inside the garage when two men arrived on a motorcycle and the passenger fired at them with an M16 assault rifle. Police found six spent shells at the scene.
Police say they believe the shooting was motivated by a business conflict.