Two rangers were killed and four others injured when separatist militants ambushed their patrol unit on a Pattani road on Tuesday night.
Nong Chik police station was alerted that a firefight had broken out on a road in Ban Don Na village in Tambon Bang Khao and dispatched reinforcements.
Police said the six rangers were patrolling on three motorcycles when they came under fire from a group of insurgents.
The rangers fired back and a five-minute gunfight ensued before the insurgents retreated and the rangers could radio for backup.
Pattani Taskforce commander Maj-General Jatuporn Klumpasut on Wednesday morning dispatched some 100 troops and police to the village to hunt for the attackers.