The victims were identified as Allan Aranatoc, 30, an employee at the Sultan Kudarat Water District, resident of Barangay San Pablo, and Mario Lagada of Barangay Buenaflor.
Bystanders in the area rushed the victims to St. Louis hospital nearby, but attending physicians declared him dead on arrival.
The duo sustained stab wounds in various parts of their body.
Tacurong police identified the suspect as Crismos Freno, a resident of Barangay Ledesma.
Reports reaching the Sultan Kudarat Police Provincial Office said that the victims were having a drinking spree in a store along Ledesma Street when the stabbing incident occurred.
According to the Tacurong police, Freno allegedly bought cigarettes at the store and without saying any word stabbed the victims with a long knife.
The suspect immediately left the crime scene on board a bicycle.
The motive of the killings was still unknown.