The violence took place in the city of Yala, where at least four explosions were reported, said police Col Prayong Khotsakha.
The most serious of the assaults was a car bomb that detonated in front a furniture store, triggering a blaze that burned nearby homes and caused numerous casualties, he said.
Other explosions were reported in the city. One bomb was hidden on a motorcycle, and another blew up an ATM.
More than 5,000 people have been killed in Thailand's three southernmost provinces since an Islamic insurgency erupted in 2004.
