The accident took place near Mohammadpur village when the speeding truck collided head-on with the Multi Utility Vehicle (MUV) which had the family on-board killing six on the spot, Inspector of Surajharha police station Neeraj Kumar said.
The family hailed from Giridih district of Jharkhand.
They were returning from Munger after attending a wedding function, he said adding the driver of the Bolero was injured and admitted at a government hospital.
The driver and cleaner of the truck fled after the incident, the inspector added.