Police in Thailand's violent south say suspected Muslim militants killed six people and wounded another Friday in coordinated attacks.

Authorities said suspected insurgents detonated a bomb buried in a road, as a truck carrying six defense volunteers drove to the scene of an earlier shooting at a rubber plantation.

Five of the volunteers were killed and one was severely injured by the blast in southern Narathiwat province, one of three Muslim-dominated provinces bordering Malaysia.

The security forces were heading to a rubber plantation, where a rubber tapper had been shot to death overnight.

More than 4,600 people have been killed in violence in southern Yala, Pattani and Narathiwat provinces since a Muslim insurgency began there in January of 2004.