Sanjay Kumar and his 11-year-old son Kannu died on the spot while wife Asha Devi was injured in the accident yesterday, police said.
They were riding a scooter and the vehicle hit them from back at Mian Bagh on Dhar Road in the district.
The woman, Asha Devi, was seriously injured in the accident, police said.
Driver of the vehicle has been arrested and a case has been registered at Udhampur police station, they said.