Police said the three are being treated in Zonal Hospital Dharamshala while others have been shifted to the Tanda medical college hospital.
There were only 8 children in the van and two escaped unhurt.
The local MLA Sudhir Sharma, who is the state Minister of Urban development released a sum of Rs 10,000 each to the seriously injured and Rs 5,000 to others being hospitalized as the quick relief.
Police said they had registered a case against the driver of the vehicle.
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