Deputy Superintendent of police H A Rathod, Nadiad division, said what started with slogans demanding better civic amenities turned violent as the people began to throw stones at the mamlatdar (tehsil officer) office.
Rathod himself was injured in the stone-pelting, and finally the police had to lathi-charge and lob nine teargas shells to disperse the mob, he said.
The protest was about long-unfulfilled demands regarding sanitation, roads and drinking water facilities, he said.