The incident was caught on CCTV but police are still clueless on the motive of the shooting.
Philippine National Police regional director, Chief Supt. Amador Corpus, ordered the city police to investigate the shooting.
The victim was identified as Rosana Agrano, 46, a female agent of the Public Safety Savings and Loan Association, Inc. (PPSLAI).
The CCTV footage showed the gunman wearing long sleeve shirt, short pants and sandals sneaked behind Agrano, who was walking along the road shoulder, before shooting her in the head.
The suspect was seen running back after the incident while the victim was sprawled on the ground.
A nearby police compact station responded to the incident and brought the victim to the hospital.
According to the security guard of the nearby Sacred Heart Medical Center, the victim was rushed to the emergency room at around 3:15 pm but was transferred by her relatives to the JBL Regional Hospital in the City of San Fernando at around 6:45 pm where she remains in critical condition.
The initial investigation showed that Agrano is a resident of EMS Barrio community just outside Camp Olivas, the headquarters of the PNP Regional Office 3. She reportedly owns a sari-sari store and works as an agent of the PPSLAI, which is located inside the regional police camp.
The PPSLAI offers loan and savings services to officers and employees of the PNP, Bureau of Fire Protection, and Bureau of Jail Management and Penology.
The shooting incident happened just a few meters from the Punto Central Luzon office.