Hundreds of Maoists attacked the Dilaru based aqueduct and canal system and blew up a newly constructed bridge in Aurangabad district, approximately 180 kms south of Patna, late evening Wednesday.
The Maoists fired several rounds to create panic after they had bombed the bridge, police said.
Aurangabad town is situated on national highway, popularly known as the Grand Trunk Road.
Sources said, hundreds of Maoists descended in mufti at the construction site of the MBL and torched three dumpers.
The company had been engaged by the Bihar government on contract to link the roads.
Police said, the Maoists later melted in the the night after about half an hour of its operations. The workers were missing and were reported to have fled the area, though there was no confirmation on whether the Red squads had taken some away.
The Maoists have been on the rampage in South Bihar, extracting levy from construction agencies, which have contracted to build roads, bridges and aqueducts under an ambitious programme of the state to link all villages.
Eye witnesses said over phone, that the Maoist firing could be heard from miles away as were the explosions.
Aurangabad is just 60 kms west of Bodh Gaya, where serial blasts were carried out on July 7 last week.