A bomb exploded at a tea shop Wednesday near a busy market in violence-plagued southern Thailand, killing at least three people and injuring more than a dozen, police said.

The bomb was attached to a parked motorcycle and triggered by a mobile phone when a military truck pulled up to the tea shop in the municipal township of Pattani, said police Col. Prasert Chansawang of Pattani province.

CountryWatch: Thailand

Police believe soldiers were the target of the explosion, which occurred near an outdoor market that is popular with military stationed in the area, Prasert said.

One soldier was killed and three were among the 16 people injured. Two female Buddhist teachers, one of whom was pregnant, were also killed, police said. The women were seated at the cafe when the bomb exploded.

Suspected Muslim separatists in Thailand's deep south have frequently used mobile phones to detonate explosives. The government has ordered all mobile phones in affected provinces to be registered and has sought cooperation from neighboring Malaysia to bar roaming cross-border phone signals.

Violence occurs almost daily in Pattani, Narathiwat and Yala — the only Muslim-majority provinces in Thailand, which is mostly Buddhist. The violence has left more than 1,300 dead since a Muslim insurgency flared in January 2004.