The incident took place today when the procession was taken out on the occasion of Ram Navami, Jalandhar Police Commissioner P K Sinha said.
The driver of the truck lost control over the vehicle and it ran over the people at the busy Jyoti Chowk area, he said.
All the injured were rushed to Sadar hospital where three persons were declared brought dead and the injured are undergoing treatment, Sinha said.
The driver of the truck was taken into custody and he has been sent for medical examination, he said, adding the truck has been impounded and it will also be sent for examination.
Meanwhile, eyewitnesses claimed the incident took place as the truck's brakes failed but the Police Commissioner refused to comment over it.