Four people were killed and 35 others injured when a passenger minibus plunged into a ravine in the southern Philippines, a town official said Monday, according to dpa. The minibus was negotiating a sharp downhill curve on Saturday when its brake system malfunctioned and fell into a 20-foot ravine in Upi town in Maguindanao province, 960 kilometres south of Manila. Upi Mayor Ramon Piang said three of the fatalities died on the spot, while another expired while being treated in a government hospital in nearby Cotabato City. Witnesses said the bus was overloaded, with some of the passengers sitting on its roof.