Two school children were among eight people injured by shrapnel from a roadside bomb near a park in Thailand's restive southern province of Songkhla on Monday.
Among the injured were a district assistant chief, a defense volunteer and villagers.
The Thai Army's Region 4 Forward Command said it believed that southern insurgents detonated the device when a converted pickup truck passed the spot. The explosion blew the vehicle off the road.
The explosion came after Sunday night's clash between the Thai Army and a group of insurgents. Five suspected southern insurgents were shot dead by security forces on a mountain in Narathiwat Province.
After the clash, Col. Pramote Prom-in, spokesman of the army's southern command, warned of possible imminent retaliation from insurgent groups.
The separatist insurgency in Thailand's largely ethnic Malay-Muslim provinces of Yala, Pattani and Narathiwat has killed nearly 7,000 people since 2004.
The Thai government is in negotiation with several insurgent groups for peace talks.