Vicente Tomazar, Cordillera chief of the Office of Civil Defense, identified the fatalities as Joseph Sari, Johnson Almeda and Jose Liwan, barangay chairmen of Camps 1 and 4 and Ansagan, all in Tuba town, respectively; and Pepe Pada of Baguio City.
Both Sari and Pada died on the spot. Their companion, Richard Abanse, a Baguio resident, is still in critical condition at the hospital.
The groups topdown jeep was rammed head-on by the bus which was carrying 39 students of the Ramon Magsaysay Technological University in Zambales at about 4:30 p.m. along the highway in Barangay Taloy Sur, Tuba town.
The students were on a study tour of the Ambuclao Dam in Bokod, Benguet.
Tomazar said the bus lost its brakes while it was negotiating a curve along the Marcos Highway, causing it to smash into the upward-bound jeep.
Last week, eight passengers of a Norton bus bound for Kabayan, Benguet were killed when the driver reportedly lost control of the wheel, sending the vehicle plunging into a 200-foot deep ravine.
Authorities said the Norton bus company had long been ferrying passengers along the Baguio-Nueva Vizcaya route despite the absence of any government permit.