Catholic station dxND, an outfit of the Oblate congregation, reported that the nuns were on their way to their monastery in Davao del Sur from a religious affair in Kidapawan City when their van lost its brakes, wiggled and turned turtle at a busy stretch of the Cotabato-Davao Highway.
The victims were rushed to a nearby dispensary and later transferred to a hospital in Davao City.
The accident occurred three days after a wayward 20-ton truck rammed into an overloaded tricycle in Pigkawayan, North Cotabato, killing six passengers, three of them on the spot, and injuring two others.
Police said the truck, bound for Cotabato City from Midsayap, North Cotabato, overtook a vehicle but smashed into the tricycle when its driver lost control of the wheel.