The incident occurred last night when members of the family and their neighbour, who were returning from Manikaran, were hit by a speeding vehicle near Banala.
Their Tata Nano car rolled down into the river and they were washed away with the flow of the water, SP, Mandi, Prem Kumar Thakur said, adding only one member of the family survived who has been hospitalised.
Today, police has been able to locate one body and the search operation is on to trace the other seven, Thakur added.