Villanueva police said three of the victims are between 25 to 35-years-old and the fourth is a minor.
A witness told police he was driving his motorcycle on his way home when he saw blood from one of the victims lying on the curved and uphill portion of the road.
The witness said the three other victims were standing beside the road, prompting him to report his grim discovery to his superior who in turn called the police.
Initial investigation revealed that the victims were possibly abducted from different locations and transported to the area and summarily executed. The victims sustained bullet wounds in the head and body, killing them on the spot.
Examination by the Scene-of-the-Crime Operatives (SOCO) led by Police Lt. Jameson Albior revealed that the victims were hogtied using tie wires and their mouths were covered by duct tape.
Police recovered five fired cartridge cases from a caliber .45 and three fired cartridge cases from a 9mm in the area.
Lawmen have conducted a follow up investigation to identify the suspects as well as the motive of the killing.
Police have secured all closed-circuit television camera footage in the area for review and coordination with neighboring towns is ongoing to identify the victims.