A three-year-old child identified as Anku, another Chander Mandal (36), a tempo driver were killed on the spot while another unidentified woman succumbed to injuries at hospital later, DSP Manoj Kumar said.
The injured were admitted to Purnia Sadar hospital and two among them were stated to be critical, he said.
Villagers, protesting the incident, blocked NH-31 for three hours demanding adequate compensation for the victim's families.