Police Major Kaow Kosaiyakanon was killed when a man posing as a buyer entered his combination house and grocery store, shot him and fled on a motorcycle, police Lieutenant Praman Yakphan said on Thursday.
Kaow, 53, of Yala province, is the most senior police officer to be killed in Thailand's Muslim-dominated south, where escalating violence has left more than 400 dead this year.
The government blames Muslim separatists, while Islamic leaders cite discrimination and officials' heavy-handed tactics against the religious minority. Outside the south, most Thais are Buddhists.
Rail workers killed
Also on Thursday, two railway employees, Yaya Phanpakdee and Amorn Payungyat, were fatally shot while inspecting tracks in Narathiwat province, police Lieutenant Suvit Phoosathit said.
In neighbouring Pattani province, district official Jehsae Jehma was shot dead while driving to his fruit plantation, police Captain Viphat Suwanarat said.
Muslims cite discrimination in the
predominantly Buddhist country
Also on Thursday, Buddhist monk Suwan Keawpradit was on his way to a religious ceremony in Songkhla province when a man on a passing motorcycle shot him in the stomach and back. Police officers, who asked not to be identified, said the monk was rushed to a hospital in critical condition.
On Wednesday night, an armed group broke into police Sergeant Thawee Boontrap's house in Songkhla province and fatally shot him.
In separate incidents the same night, assailants shot to death Boosaw Saeseng, 72, and Nikhom Somphaeng, 40, in Narathiwat province.
Living in fear
"Buddhists are living in a state of fear because we find that the insurgents are now targeting us. They are exacting revenge on innocent Buddhists who have nothing to do with the ongoing violence," Pairat Wihakarat, president of a teachers association in southern Thailand, said.
One local official was beheaded this week in an apparent act of revenge, while warnings that Muslim fighters may try to abduct Buddhist teachers and students prompted most schools in the country's three southernmost provinces - Narathiwat, Yala and Pattani - to close until at least Monday.
A total of 85 Muslims protesters
suffocated in army trucks
"Many people have sold their property and taken their children out of the region, but for us we have no choice," Pairat said. "We have no place to run to."
Large numbers of students were transferring to schools outside southern Thailand, he added.
Deaths by suffocation
Pairat was referring to revenge for the 25 October deaths of 85 Muslim protesters, most of whom suffocated while jammed into army trucks after security forces detained them.
Dr Pornthip Rojanasunan, a well-known pathologist in Thailand, said she and a team of doctors conducted autopsies on 78 bodies at an army camp in Pattani province and found that most of the dead had perished from suffocation.
"Seventy-eight people died from suffocation. We found no wounds on their bodies," senior justice ministry official Manit Sutaporn said in Pattani.
The dead were among some 1300 people arrested on 25 October following a demonstration in Thailand's Muslim-dominated southern provinces, which have been hit by unrest this year.
Army units deployed
Thailand's army chief General Pravit Wongsuwan said the army was deploying units after the United Nations warned its employees to exercise "extreme caution" in the south.
A travel restriction in the south "may become necessary" if things worsen, said the 26 October internal UN e-mail, seen on Wednesday by the media.
The Pattani United Liberation Organisation's website urged Buddhists to leave the south and has threatened attacks in Bangkok.