Police suspect that Maoists kidnapped them after contractor Pawan Kumar Singh refused to pay levy or extortion.
Singh told the police that Maoists demanded levy for continuation of road construction work or threatened him with dire consequences.
The fear of Maoist guerrillas has put a stop to road construction in many parts of rural Bihar. Contractors in several projects have fled, fearing for their lives, an official said.
Last year, Maoist guerrillas demanded Rs.220 million from the Hyderabad-based Engineering and Construction Inc (ECI) that was building roads in Rohtas.