The police said that the mishap took place near Dhanushi village when a mini truck rammed into an autorickshaw carrying eight passengers amidst thick fog.
Three of the victims have been identified as Ravi Kumar (12), Rambabu Paswan (45) and Shrawan Kumar (14), the sources said, adding the bodies have been sent for post-mortem.
The injured were admitted to the Sadar hospital for treatment where the attending doctors referred two critically injured persons to the Patna Medical College and Hospital (PMCH).