According to the police, Rakesh (35) along with his wife Rajkumari, son Deepak (8) and daughter Teena (3) boarded a truck in Etawah for Fatehpur district.
The accused truck driver stopped at a roadside eatery and asked Rakesh to fetch some food, while his wife and two kids stayed back, they said.
In the meanwhile, the driver drove away with the woman and her two kids. He attempted to molest Rajkumari to which she objected.
The mother-son duo was taken to a hospital where Rajkumari died during treatment, they said.
Police said the driver escaped with Rs 3,000, half kg silver and other belongings of the family.