The Yala police chief has ordered his officers to tighten security after a series of deadly blasts in Rueso district in nearby Narathiwat province on Saturday.
Two bomb blasts in Narathiwat killed two people and injured more than 10.
Police will release sketches of two suspects seen on CCTV footage near a house behind Rueso police station _ the site of a car bomb that killed two people. Police will also seek arrest warrants for the pair.
The second explosion, which involved a motorcycle, took place near Ban Yaba Uppakara Witthaya school.
The two attacks happened a day after Prime Minister Yingluck Shinawatra took charge of national security operations.
Yala police commander Pol Maj Gen Peera Boonlieng said further violence could spill over from Narathiwat into Yala, so he urged his officers to remain vigilant.
Pol Maj Gen Peera said he ordered police to beef up security to prevent further bomb attacks.
He said he ordered police to set up checkpoints on main provincial roads and on inter-district routes.
"We have information that insurgents have stolen several motorcycles and cars," he said, adding that it is believed the stolen vehicles are outfitted with explosives to be set off in public places.
He said his officers were tracking down a stolen Isuzu D-Max and a golden-bronze Toyota pickup following information that the two trucks would be used in car bomb attacks in the southernmost provinces.
Pol Maj Gen Peera said additional police patrols have been assigned to increase surveillance of several locations and to check whether CCTV cameras were correctly placed and in working order.
Violence continued in the South yesterday. Chula Woma, 33, a teacher at Ban Kaen Thao School in tambon Ko Chan of Mayo district in Pattani, was shot by a pillion rider on a motorcycle as he waited at a bus stop on the Pattani-Yala road near Ban Ton Kham in tambon Mo Mawi. He was seriously hurt and taken to hospital.
In Pattani's Khok Pho district, Tasmi Kabae, 40, of Yarang district, was shot dead while riding a motorcycle on the Ban Khok-Ban Prang road.
An unknown number of people opened fire at him with a 9mm pistol about 1am, hitting him four times in the body. He died at the scene.
Meanwhile, government forces killed a suspected militant during a shootout in Songkhla's Saba Yoi district early yesterday morning.
The clash occurred when police surrounded a house in a village in tambon Chumpho in Saba Yoi district after receiving information that a number of militants were hiding there. A 10-minute exchange of fire ensued. The deceased was identified as Mayuding Sama, a native of tambon Sapae in Yaha district of Yala province. Two others in the house escaped.
Authorities said a 50kg bomb was found in Narathiwat's Si Sakhon district, which was successfully defused.
Two fake bombs were also found in Chanae district of Narathiwat yesterday morning. Pol Col Patta Madava, the Chanae police chief, said a bomb disposal team was deployed to a village in tambon Dusongso after residents reported seeing two suspicious objects.