The bomb exploded Thursday on a road in the Bannang Sata district in Yala province as government-hired paramilitary rangers drove by, killing 10 of them instantly, said Thai Army spokesman Col. Akara Thiprote. Another ranger died later at the hospital.

Almost immediately after the bombing, an unknown number of assailants opened fire on a group of Muslim villagers leaving a mosque after evening prayers in nearby Sabayoi district of Songkhla province, killing five villagers at the scene, Akara said. Two others died later at the hospital.

It was not immediately clear why the worshippers were attacked but officials blamed Muslim rebels.

"The insurgents opened fire on the Muslim villagers and put the blame on the authorities ... They want to create an impression that authorities cannot take care of the Muslim people in the area," Akara said. "Worse still, they want people to think the authorities did it to poison the relationship between the government and the local population."

Thai military authorities have blamed such attacks on Muslims bent on intensifying hatred against the government and to radicalize Muslims and push them into joining the insurgency.

Some Muslims believe the security forces, or even Buddhist vigilantes, might have a hand in the attacks.

Since a Muslim rebellion flared in the three southernmost provinces in early 2004, near-daily bombings, drive-by shootings and other attacks have killed more than 2,200 people.