A bus ran off a slick mountain road into a ravine in northern Peru on Saturday, killing at least 33 people, police said. Rainy, pre-dawn conditions made for poor visibility when the vehicle plunged off the highway about 900 kilometers north of the capital of Lima, local police Capt. Jose Cotillo said. Highway police commander William Vasquez said the bus was traveling to the northern city of Querocoto. A witness to the crash, Emiliano Fernandez, told radio station Canal N that he saw the bus swerve off the road. "When we got to the canyon to help, we only heard the cries of the people from the bottom," he said. Rescuers transported 23 survivors with injuries to nearby towns including Chiclayo for treatment.