A state telephone company worker has been killed in the latest attack in Thailand's mainly-Muslim restive south.
An investigation into the attack on the teachers is under way
The man, reportedly a Buddhist, was riding his motorcycle to work when he was shot dead and then set on fire in Pattani province, officials said.
Meanwhile, many schools across the region have closed after two women teachers, both Buddhists, were attacked and beaten in a village last week.
One of the women is unlikely to recover from her wounds, doctors say.
More than 1,300 people have been killed since the violence escalated in the far south, close to the Malaysian border, in January 2004.
The government blames Islamic separatists for much of the unrest, although criminal motives are thought to also be at work.
Police said the latest attack happened in the Saiburi district of Pattani province.
"The attackers opened fire on him and then set fire to the motorcycle to burn the victim," said police Maj Gen Korkiat Wongworachat. "It was a very cruel act by the insurgents."
It comes as education officials in neighbouring Narathiwat province decided to close 100 schools in the area for a week following the attack on two teachers in Rangae district.
Thawat Sae-Hum, head of a teacher's union in Narathiwat, said "teachers are scared and they have no confidence their security will be protected".
The two teachers, aged 24 and 30, were dragged from their school in Kujing Ruepa village on Friday by angry villagers.
Home to most of Thailand's 4% Muslim minority
Muslim rebels fought the government up to the mid-80s
Suspected militants have upped attacks since 2004, targeting Buddhists
Security forces' response criticised by rights groups
They were held hostage and severely beaten by attackers who were demanding the release of two Muslim men arrested in the village earlier on suspicion of killing two marines.
The newly-graduated 24-year-old teacher remains in a coma, doctors said.
"Only a miracle can bring her back to consciousness," Sumet Pirawut, head of the hospital treating her, told a radio station in Bangkok.
This is the fourth time this year that teachers have been taken hostage, although have been killed, according to Reuters news agency.
Teachers are often targeted as they are seen as symbols of Thailand's Buddhist authorities.
Head of security for the region, Lt Gen Ongkorn Thongprasom, has offered to quit following Friday's incident.
"I am deeply sad that such a brutal incident took place," he said, adding that he took full responsibility for it.