The victims were attending a mid-week prayer meeting on Wednesday evening when the attack happened at the parish of the United Church of Christ of the Philippines in Pikit town in North Cotabato province, 930 kilometres south of Manila.
The suspects used a grenade launcher in the attack, said Senior Inspector Mautin Pangandigan, the town’s police chief.
Investigators were still determining a motive for the attack that killed a 54-year-old nurse and a 39-year-old teacher, he added.
“We have no idea why this attack happened,” said Pastor Jerry Sanchez, who was leading the prayer meeting. “We condemn this act.”
Past bombings and grenade attacks in the province have been blamed on Islamist militants opposing a peace deal in the southern Philippines or communist rebels.