Thai police allege that the attackers fired at security checkpoints in Southern Thailand and killed at least 15 volunteers.
Police colonel Thaweesak Thongsongsi, police chief in Yala province, said that an unknown number of assailants used a heavy weapon in the attack late Tuesday, which also injured five volunteers.
The Bangkok Post reports that 11 of the victims were killed on the spot and four others died at Yala Hospital.
A Muslim separatist armed campaign has left about 7,000 people dead since 2004 in Thailand's three southernmost provinces of Yala, Patani and Narathiwat.
Police, teachers and other government officials are often subject to violence.
At least two other outposts in the area have also been attacked but no casualties.
A small explosive was found near an electric pole to knock out electricity, and nails were scattered along a highway to deactivate vehicles entering Yala.
Several burning tires were left at school.
According to the Bangkok Post, at least three ambulances were also damaged and several rifles were taken. beaten so severely during a military interrogation that he became comatose. He later died of his injuries.
The army stated that there was no evidence of torture.
Mara Patani, an umbrella group representing some factions of armed rebels, called for international intervention after the Abdullah case – a request rejected by the Thai army.
Al Jazeera and news agencies