HAT YAI, Thailand -- Gunmen disguised as state security personnel fatally shot four paramilitary volunteers guarding a school in insurgency-wracked southern Thailand, police said.

The attackers approached the armed territorial defense volunteers at the school in Pattani province and shot them dead shortly before noon Thursday, police Lt. Col. Wicha Nupannoi said. They seized four HK33 assault rifles from their victims before fleeing, scattering nails and other material on the road to delay pursuers, he said.

Predominantly Buddhist Thailand's three southernmost provinces of Pattani, Yala and Narathiwat have been plagued by a Muslim separatist insurgency that has claimed the lives of about 7,000 people since 2004, according to the research group Deep South Watch, which monitors the region.

On Tuesday, a bomb outside a school and a car bomb elsewhere exploded in nearby Songkhla province, wounding a 12-year-old student, a security guard for teachers and a police medic. A flurry of similar attacks took place in the last week of December. Several targeted Songkhla, which previously had been largely spared the violence.

"The insurgents consider school officials to be symbolic of the Thai Buddhist state's occupation of Malay Muslim territory," Human Rights Watch said in a statement. "They have frequently targeted security personnel assigned to provide students and teachers safe passage to and from school, or protecting the school grounds."

The attacks have occurred during an effort to revitalize peace talks between the Thai government and some insurgent groups. Analysts say the most militant group, the Barisan Revolusi Nasional, is not taking part.

Thai Defense Minister Prawit Wongsuwan blamed the BRN for Tuesday's bombings. He said the authorities would have to step up efforts to prevent the attacks.

Human Rights Watch also pinned the blame for the region's ongoing violence on the BRN.

The insurgents "attack schools and medical clinics to maim and terrify Buddhist civilians, control the Muslim population, and discredit Thai authorities," Brad Adams, the group's Asia director, said in the statement. "Whatever the rationale, targeting civilians is morally indefensible and a war crime."