At least eight people, including three women, were killed and 40 injured when a private overloaded bus skidded off the road and fell into a gorge in Himachal Pradesh's Solan district on Saturday, police said.The accident took place near Darlaghat, 80 km from Shimla. The bus was on its way from Shimla to Mandi town with 50 passengers on board.The cause of the accident is not known. Witnesses said rash driving and bad condition of the road were mainly to blame.Some of the injured have been referred to the Indira Gandhi Medical College and Hospital in Shimla for treatment.Governor Acharya Devvrat and Chief Minister Virbhadra Singh have expressed grief over the accident.