The incident happened last night at 11 PM when a family was returning from Kannuaj in the tempo. The speeding truck from Bilhor hit the tempo at G.T. Road after which the tempo overturned, they said.
Shiv Singh(47), Nathuram(40) and Dileep(15) died on the spot, police said.
The other four injured were taken to Helat Hospital, they said, adding that their condition is serious.
After the accident, the truck driver fled from the scene, they added.