The four men were shot dead in Narathiwat province, and included a village headman in Sungai Padi district and a village security guard in Sri Sakhon district, where assailants attacked houses storing weapons for defence volunteers late on Wednesday.
Another village headman was shot dead outside his house in Rangae, and a villager was killed by gunfire in the same district, police said.
More than 20 guns were stolen when an unknown number of attackers raided at least 17 areas in Narathiwat province in the wave of attacks that began around 8pm (1300 GMT) on Wednesday, police said.
In an ambush on the house of a village headman in Yala town, Yala province, one suspected fighter was wounded when the headman fired back, police said.
Police were also responding to a suspected ambush in Pattani province late on Wednesday, but few details were available, officers said.
Thai defence minister says the
military will get more aggressive
The attacks came a day after Thailand's cabinet approved spending almost $16 million on more than 20,000 M-16 assault rifles for its security forces operating in the troubled south.
Nearly 1000 people have been killed in the Muslim-majority south since the bombings, shootings and arson attacks began in January 2004. Analysts and authorities blame the almost daily attacks on Muslim separatists, organised criminals and local corruption.
Thailand is predominantly Buddhist, but up to 10% of the country's 65 million people are Muslims, most living in the three southernmost provinces, where they have long complained of second-class treatment.
The feeling of alienation has contributed to several separatist rebellions in the area over the past century.
Tactics from Iraq
Earlier on Wednesday, police said the southern separatists had adopted the same tactics as those in Iraq and Indonesia, and their violence has caused 450 deaths so far this year, and 668 the year before.
"The insurgents have been using the same tactics of attack that the terrorists do in Iraq and Indonesia, which results in a large loss of life among innocent people," police Lieutenant-General Achirawit Suphanaphesat, spokesman for National Police Bureau, said at a news conference in Bangkok.
"The insurgents have been using the same tactics of attack that the terrorists do in Iraq and Indonesia, which results in a large loss of life among innocent people"
Lt-Gen Achirawit Suphanaphesat,
National Police Bureau spokesman
He did not elaborate, but other officials have noted the increased use of bombs detonated remotely by mobile phone, and more sophisticated tactics against government security forces.
"The security forces in the region need to adjust their strategy from the defensive to be more offensive to counter the insurgents and to protect the lives and property of people," Achirawit said.
He did not say what a change in approach would involve, but his remarks echoed those of Defence Minister Thammarak Isarangura na Ayuthaya, who recently said the military will take on a more aggressive approach.