An oil tanker truck driver and his assistant were shot dead by hijackers in Rosario, La Union. 

The victims were shot multiple times and left in a roadside canal by the suspects.

According to police investigation, four men posing as uniformed personnel intercepted the oil tanker truck. 

The suspects forced the two victims out of the truck and shot them in different parts of their bodies.

"Posible ang target talaga nila is ‘yung truck," Jake Isidro, Public Information Officer of the La Union Police Provincial Office (PPO), said.

In a follow-up operation, police recovered the truck in Aguilar, Pangasinan. The truck may have been abandoned due to mechanical issues.

With the help of a witness, police arrested one of the suspects during an operation in Sual, Pangasinan.

The suspect is now in police custody and has yet to make a statement. The police have also identified the remaining three suspects.

"Maganda naman ang takbo ng investigation with the coordination ng ibang kasamahan sa PNP (Philippine National Police) ay naaresto ang suspek sa Sual, Pangasinan," Isidro said. 

Remains of the assistant, Ariane Casabueno, 32, now lie in Barangay Tococ, Sto. Tomas. He leaves behind a wife and three children. 

"Talagang naiiyak ako, wala akong masabi sa aking manugang, sobrang lupit ang nangyari. Sobrang bait niya, talagang ginawa niya ang kanyang karapatan para itaguyod ang kanyang mga anak," Rolando Rivera, Casabueno's father-in-law, said.

The driver's family in Agoo, La Union, declined to make a statement.