The stretch, which was declared as green belt, was sold by the some builders to people even after repeated warning by authorities.
The authorities faced stiff resistance from locals who pelted stones and burnt tyres on roads between from Gaur City till Tigri village, police said.
It took half-an-hour to Bisrakhs police team and police force from other nearby police stations and PAC battalion to quell the resistance.
Some policemen and residents suffered minor injuries in the skirmish.
After that authority bull dozers demolished the unauthorised construction from Gaur City till Tigri village.
Residents claimed that they were told by the dealers at the time of purchase that the plots did not belong to authority.
However, District Magistrate MKS Sudaram, said that he had warned the public not to buy land in flood zone area.
