The clash broke out at about 3.50am after rangers surrounded the house where insurgent suspect Mahama Maeroh, 29, was hiding.
“The exchange of gunfire lasted more than 10 minutes. After the gunshots stopped, we found Mahama was dead,” 46th Rangers Regiment commander Colonel Pasit Charnlekha said.
He said rangers also arrested three other suspects at the scene.
Rangers had been on Mahama’s trail for three days before they found him at the house, Pasit said.
Mahama was wanted in connection with at least six incidents, including four attacks in Narathiwat province and two in Yala.
Officials said Mahama was shot three times during the gunfight.
“His body will be sent to a hospital for an autopsy. After that, we will contact his relatives so that they can collect his body for religious funeral rites,” an official said on condition of anonymity.
Authorities have said that Mahama led a group of about six insurgents who had been active in staging attacks in the deep South, particularly in Narathiwat.
Authorities reportedly instructed security officials in Narathiwat to be extra vigilant based on a theory that the RKK might stage revenge attacks.