Gunmen killed 10 people and wounded 12 others at a mosque during evening prayers in the south of Thailand on Monday.
Colonel Prinya Chaidilok told Channel 11 television that five gunmen with automatic weapons opened fire while their victims kneeled on the floor praying.
The attack took place in the Cho Airong district of Narathiwat.
It is one of three mainly Muslim provinces where more than 3000 people have been killed in the past five years.
A rubber tapper was also shot dead and nine soldiers were wounded by a roadside bomb on Monday.
Nineteen people have been killed and 40 injured since Friday.
The region was an independent Muslim sultanate until annexed by Thailand a century ago.