A bus plunged early Friday into a snowy mountain ravine in a remote area of northern Pakistan on Friday, killing at least 19 passengers and injuring four others, police said. The accident happened during snow fall in the Kohistan region, about 400 kilometers (240 miles) northeast of Peshawar, the capital of North West Frontier Province, said police officer Jamal Khan. The bus was traveling between the towns of Abbottabad and Gilgit. The cause of the accident was not immediately clear. Khan said the dead and injured have been transported to a local hospital.