A tourist bus packed with Iranian nationals plunged into a ravine Sunday while negotiating a mountain road in the central Philippines, killing at least 18 people and injuring more than 30 others, officials said. The bus, carrying dozens of mostly Iranian medical students and doctors, apparently suffered brake failure then plummeted into a 100-foot (30-meter) ravine in Balamban town in Cebu province, police Senior Superintendent Erson Digal said. At least 18 people, mostly Iranians and including children, were killed, said regional military spokesman Lt. Col. Wilson Feria, who was at the scene of the accident. Villagers and police pulled at least 10 bodies from the mangled bus wreckage at the rocky bottom of the ravine.