At least six people were killed and over 20 injured Friday in three road accidents in Pakistan.According to officials, a bus plunged into a deep ravine in Khyber Pakhtunkhwa's Abbottabad city and left four people killed and five others injured, Radio Pakistan reported.In Punjab province's Faisalabad city, two motorists were killed in an accident caused by poor visibility due to dense fog.Over 15 people were injured when a passenger coach overturned at Balochistan province's Hub town.