The tragedy took place when the bus, with 56 onboard, was on its way to Tunni village from Vikas Nagar at around 9 am in the morning. It fell into the Tons river after skidding from the curvy road. 12 persons are said to be critically injured.
Tons river is a largest tributary of the Yamuna and due to strong water currents most of the passengers drowned in it. Latest reports say due to the immense depth of the river, the bus was out of sight.
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PTI report says police along with medical and rescue teams have been mobilised from Sirmaur and Shimla districts to help in rescue and relief operations at the spot, about 190 km from here. Help of locals are also being used.
According to Wikipedia, the top of the Tons river is in the Himalayan Crystalline complex. It then flows through Tethan Himalaya rocks before connecting to the Pabbar River in the Lesser Himalayan Sequence. The Tons flows into the Yamuna River after crossing into the Sub-Himalaya Sequence.
More details are awaited.