One of the dead officers was considered a national hero for his work in defusing hundreds of bombs, the Bangkok Post reported.
Maj. Gen. Pattanawut Angkhanawin, chief of the Narathiwat provincial police, said the squad had been been lured to the area by tires set afire on a highway. They were examining a hole along the highway for a possible explosive when another bomb buried nearby detonated.
The explosion hurled the bodies of Police Sub Lt. Chaen Warongpaisith and two other officers about 130 feet. A fourth officer was wounded.
Other bomb squad members later found and destroyed a third bomb.
Chaen, 50, was reported to have defused at least 200 explosive devices in the conflict-plagued province. He had received several awards for his work and survived three shootings and five bombings.