Eight others, including the two drivers, were injured in the incident, police said.
The victims -- Pappu (25), Chanda Mali (27) and Devilal (40) -- had gone to attend a funeral at a cremation ground along the road and were sitting on the roadside when the accident took place.
Police said the driver of the dairy van suddenly applied brakes leading to the collision.
The injured had been rushed to a hospital, where doctors said the condition of one of them was critical.