The incident took place on Muzaffarpur-Pusa road under Mushari police station area when an autorickshaw hit a motorcycle on which the couple was riding with their two children, Mushari police station in-charge Vikas Rai said.
All four fell down from their bike and a speeding truck crushed the couple under its wheels, while their two children sustained injuries, he said.
The bodies have been sent for post-mortem and the injured children admitted to a government hospital for treatment, he said.