Four plainclothes soldiers were shot dead on Wednesday in an ambush by unidentified gunmen in Thailand's southern province of Yala, police said.
"The four in a personal car were on their way back to their base when they were shot dead ... It is expected to be an act of insurgents," district police official Chanvut Rugsapram in Yala told Reuters by telephone.
Last month, 18 people were wounded in a string of bomb attacks in Yala.
More than 6,500 people, most of them civilians, have died in separatist violence in southern Thailand since resistance to Buddhist rule flared up in 2004.
Thailand's military government says it has adopted new strategies, including DNA swabbing, to curb the insurgency, although lawyers and activists say the forced DNA sweeps are further alienating residents.