Gunmen entered a mosque in Yala's Than To district yesterday and murdered two Border Patrol Police (BPP) officers praying there.
Police said four armed men entered Nurul Hibadah mosque in Ban Mayo and shot both policemen in the head at about 1.30pm.
The slain officers were identified as Pol Lt Adul Rakpratch and Pol Sub Lt Waeromlee Waehama of the 44th BPP Task Force.
It is not yet known what kind of firearms were used.
The two officers were praying when the killers pulled out guns, shot them, and then quickly fled into a crowd of local residents.
Police have blamed the incident on southern insurgents looking to cause unrest.