The attack also injured a passerby, a Muslim local resident.
Police said the attack happened at 10:50 pm on a village road of Ladu village in Tambon Sa-eh of Krong Penang district.
When the ambush occurred, a patrol unit of police, which was nearby, rushed to help the three policemen and the reinforcements exchanged gunfire with the insurgents for about ten minutes.
After the insurgents retreated, Pol Lt Col Adinan Isma-il, deputy commander of the Krong Penang police station, Pol Sub Lt Danupol Asae, and Pol Lance Corporal Hama Sarado were found dead.
The three police officers were returning from a praying rite at the mosque in the village when they were ambushed.