At least twenty people were killed and four others wounded when a passenger coach skated into a deep ravine in the treacherous mountainous areas of Pakistan's North West Frontier Province (NWFP), police said. The coach was coming to Rawalpindi, adjacent to Islamabad, from Diamer. The mishap took place around 2 a.m. Friday on the Karakorum Highway near Kairo. The coach fell in a deep ditch on the banks of the River Indus. A dozen bodies have been pulled out while rescue operation was on to retrieve the remaining ones. The injured persons were shifted to the Pattan hospital. Police said the cause of the mishap was not immediately known.