The deceased, all residents of Faridabad in Haryana, have been identified as brothers Rajendra (28) and Vinod (25) and their cousin Bali (20), they said.
The mishap took place early morning when they along with other family members were returning from a pilgrimage in two separate vehicles, one of which was hit by the truck, police said.
Another person was injured in the incident, police said, adding he was rushed to a hospital where his condition was stated to be critical.