Military-installed premier Surayud Chulanont made a surprise trip to southern Thailand late on Friday to visit victims of a bombing last week who are still in hospital.
But just an hour before he arrived, militants ambushed a Buddhist family returning to their home, killing the parents and their four-year-old daughter in Yala province, police said.
The day after his visit, a Muslim army ranger was killed in a drive-by shooting while he was off-duty in nearby Pattani province, police said.
A 74-year-old Buddhist man was also shot at point blank range while he was resting at his rubber plantation in Narathiwat province, police said.
The killings were the latest in a surge of violence in recent weeks, despite a raft of new measures aimed at ending the nearly three-year conflict that has left more than 1,500 dead.
Surayud's government last week announced that on Wednesday it would re-open a key regional mediation body, which was credited with easing previous conflicts in the region but which was dismantled by ousted prime minister Thaksin Shinawatra.
"What will be expanded from the beginning is a great role for participation by the people," the defence minister, General Boonrawd Somtas said in announcing its re-opening.
He also said the military would end controversial emergency rule in the region by January. But since the entire country has been under martial law since the coup last month, that move would only have practical effects if martial law were lifted.
The military toppled Thaksin's government in a bloodless coup on September 19, bringing down a leader who was widely despised in the mainly Muslim provinces because of his hard-line tactics.
The take-over brought a glimmer of hope for a breakthrough in the conflict, and the junta has quickly moved to undo many of Thaksin's policies that were blamed for exacerbating the conflict.
Surayud made one of his first overseas trips to neighbouring Malaysia, in an effort to mend relations that have been strained by the unrest on the border and to win support for efforts to restore peace.
But despite these moves, the violence has soared, with at least 38 people killed in the last two weeks.
Offers to hold talks with insurgents have so far led nowhere, and the government has admitted that it still does not know exactly who is behind the unrest.

Copyright AFP (Agence France-Presse), 2006