The incident took place at Banthara Nagaria outpost when the driver of a truck, carrying over 24 people, lost control and it collided with another heavy vehicle, they said.
The deceased include a 40-year-old woman, Sunita, and her daughters Alka (7) and Geeta (5). Others are yet to be identified, police said.
The injured have been rushed to a nearby hospital where their condition was stated to be stable.