HAT YAI, Thailand — Two police officers in southern Thailand were abducted and later found dead in a ditch, with the pickup truck of one of the officers stolen and set on fire, police said Wednesday.

Police are investigating whether the killings Tuesday night in Narathiwat province involved a personal dispute or were part of a Muslim separatist insurgency that has claimed about 7,000 lives since 2004.

Pol. Lt. Sarayuth Kachawong, deputy investigator of the Joh I Rong district station, said four heavily armed attackers clad in black and camouflage outfits kidnapped the two officers from a house where they were socializing Tuesday evening. They also stole a rifle and two pistols belonging to the officers before escaping in the pickup truck.

Police later discovered the bodies of the officers in a ditch with gunshot wounds, and then found the pickup truck in flames at the entrance to a nearby village.

The insurgency affects the three southernmost provinces of Pattani, Yala and Narathiwat, the only ones with Muslim majorities in the predominantly Buddhist country.

In a separate incident Tuesday morning, a remotely detonated explosive device killed a paramilitary ranger and injured two others in Yala province, said police Capt. Narongchai Vechnil, deputy investigator of the Banangsta police station. He said the ranger was patrolling the area on foot when the device exploded.

There has been an upsurge of violence in recent months attributed to a hardcore separatist faction seeking to derail peace talks between the government and other factions.