The police said junior engineer of Nagaon division Prashanta Bhuyan and two labourers - Lakshmi Hira and Bhadra Singh Konwar - died on the spot after the truck mowed them at Barpatgaon when they were returning to the nearby camp on foot this evening.
Seven other injured, three of them critically injured, people were admitted to Tejpur Kanaklata Civil Hospital.
The driver lost control and the vehicle skidded off the road. He was in a drunken state, the police.