A passenger bus fell into a deep ravine in northern Pakistan on a mountainous highway that connects the country with China, killing at least 20 people and wounding score others, officials said on Friday. The bus carrying around 40 passengers was on its way to the mountainous region of Gilgit-Baltistan from the city of Rawalpindi near the capital Islamabad, local official Fayyaz Ahmed said. Nearly 20 people were wounded in the accident and were being treated at hospitals, rescue official Dildar Tanooli said. The rescuers backed by army helicopters recovered the victims from a difficult terrain,…