One ranger was killed and two others and a civilian injured by a bomb explosion in restive southern province of Narathiwat on Wednesday morning, Bangkok Post online reported.

A witness told police that he was walking across the railway bridge in Narathiwat's Cho Irong district to the nearby railway teashop when he spotted a suspicious box tied on a pole of the bridge. He reported his finding to Matohae Sae, leader of a 20- ranger unit patrolling on foot in the village.

As the rangers walked toward the box the home-made bomb was detonated. Ranger Somchai Kamchun died at the scene while two other rangers were injured and taken to Cho Irong Hospital.

A civilian drinking tea at the teashop was also hurt by shrapnel and taken to the hospital.

Police blamed separatist militants.

Since the resurgence of insurgency in 2004, around 11,000 violent incidents instigated by secessionists in the Muslim- dominant southernmost provinces of Yala, Pattani and Narathiwat happened, with almost 5,000 people killed and nearly 8,000 injured.