The incident occurred when the victims were taking a nap in the company premises ahead of their night shift duty when the stone-laden dumper ran over them, police said.
The injured labourers identified as Nisir Mahato (30), Ramesh Mahato (50) and Bidesh Mahato (22) and Jyotilal Majhi were immediately rushed to M G M Hospital here, where doctors declared Nisir, Ramesh and Bidesh dead.
Majhi was undergoing treatment at the hospital.