Police said a manhunt for Francisco Agob, 65, of Barangay Magtanggol, was immediately launched following the incident that took place inside the victims house on Lozada street in Sta. Rosario.
Police Officer 3 Jose Abelido said Salvador Bulalacao, 30, a taxi driver, was watching television with her daughter Ma. Eliza when the suspect dropped by the house.
Initial investigation revealed that a heated altercation ensued between the suspect and his son-in-law, prompting the older man to draw his .9mm handgun and shoot the latter.
According to Abelido, it was possible the suspect had only targeted his son-in-law, but one of the bullets may have accidentally hit the girl.
The girl sustained a gunshot wound in the head while the father was shot in the left chest. Both were declared dead on arrival at the Rizal Medical Center in Pasig City.
Abelido said the suspect had fired several shots based on evidence recovered at the crime scene. Investigators found at least five slugs.
Agob fled on board his motorcycle with unknown plate number. He was not around when police went to his house.
"His wife told us that she was not aware of any standing feud between him and their son-and-law," Abelido said in a phone interview.