Two sergeants, Ruengrit Thongtip and Nares Tipsala and Police Senior Sgt Maj Sunya Jitlerm, suffered shrapnel wounds from the explosion and were rushed to Bannang Sata Hospital.
Sunya was more seriously injured and later transferred to Yala Hospital.
The initial police investigation showed that police had been riding in an official pick up on Pawang-Bannang Sata road when an explosive hidden by insurgents under sacks near an electricity pole on the roadside went off.
The blast also damaged the pick-up and a nearby truck.
Police found a hole caused by the impact of the explosion as well as some wires, shrapnel and other items believed to be parts of the explosive on the road.