Police Col. Chartchai Chanasit says two gunmen riding on a motorcycle carried out the attack today in the Bannang Sata district of Yala province.
Chartchai says another boy was injured in the attack. Last week, an insurgent was killed in a shooting in the same district that also left his 6-year-old son dead.
More than 5,000 people have been killed in Thailand's three southernmost provinces since an Islamic insurgency flared in 2004.