At least 40 people were killed and another 30 wounded Saturday when a bus plunged off a mountain road in western Nepal, police said. The bus was traveling near the town of Tribeni, some 400 kilometers (250 miles) west of the Nepalese capital, Katmandu, when it skidded off the road, plunging about 250 meters (yards) into a ravine bellow, said local police officer K.C. Rambahadur. Police are investigating the cause, he said. Deadly road accidents are common in Nepal, often caused by poor roads and aging overcrowded vehicles, the Associated Press reported.