The victims were identified as Ram Prakash (21), Surender (21) and Vikas (19), all residents of Kohli village under Adampur police station.
The incident took place late last evening, near the village, about 50 km from here, when all four youths, riding the same motorcycle, were returning to their village from Adampur, where they work.
As they reached near their village, an unknown vehicle coming from the opposite direction hit their bike killing three on the spot, police said.
A case has been registered against the driver of the unidentified vehicle. The bodies of the deceased have been handed over to their relatives after conducting the post-mortem.