Senior Inspector Joseph Sta. Cruz, Carranglan police chief, said Christy Lauyan, 37, of Bambang town in Nueva Vizcaya province, and Jennifer Tayuto, 18, of Makati City, died while being taken to the Nueva Vizcaya General Hospital in Bambang.
Sta. Cruz said the Dalin bus, which was carrying 26 passengers, came from Tuguegarao City in Cagayan province and was traveling along the mountain highway in Barangay Capintalan in Carranglan when the accident happened at 12:30 a.m.
He said trees along the mountainside highway prevented the bus from hitting the bottom of the 100-meter deep ravine.
The other passengers, who were taken to hospitals in Nueva Vizcaya and Nueva Ecija, suffered minor injuries, Sta. Cruz said.
Investigators have yet to establish what caused the accident.
The bus driver, Teody Marayag, 36, was arrested by the Carranglan police.