The 4th Army on Wednesday continued hunting suspects responsible for Tuesday night's brutal gun attack on a security checkpoint in Yala's Muang district, which left 15 village defence volunteers dead and five others injured.
Lt Gen Phonsak Phunsawat, the 4th Army chief, said a massive manhunt was being carried out for the attackers while efforts were being undertaken to provide care for the families of the victims.
He offered condolences to families which lost loved ones in the attack.
"This village has never before been considered a danger zone as there have been no reports of insurgent activity here previously," he said while visiting the scene of the carnage on Wednesday.
This latest attack pointed to a need to alter security measures involving the use of defence volunteers in manning security checkpoints, he said.
Prime Minister Prayut Chan-o-cha also condemned those behind the attack and agreed security officials should rethink their strategies.
Village defence volunteers have become a new target for southern insurgents, he said.
As for the government's peace talks with various insurgent groups, Gen Prayut said he had discussed several issues with his Malaysian counterpart who had agreed to help.
A security source said the attackers were controlled by Hubaidila Romueli, who leads an insurgent network in Yaha and Kabang districts, and Amat Tuenga, who heads another rebel group in Muang district.
The attack was believed to be retaliation for the extrajudicial killings of two insurgent suspects in Pattani's Sai Buri district last week, said the source.
Another security source said the Barisan Revolusi Nasional was responsible for recent major attacks in the deep South, which were successful because security officials have been in denial about a BRN presence in their areas but were now forced to confront the reality.