Police in Zhejiang province are searching for suspects involved in Saturday's violent protest against a proposed huge waste incinerator.
The city government of Yuhang said it would shelve plans to build the plant if it did not have popular support, following clashes that left at least 10 protesters and 29 policemen injured.
More than 30 cars were overturned, two police cars set on fire and another four were smashed up, Xinhua said.
Police issued a "wanted-style" notice with pictures of 15 suspects, calling on them to hand themselves in for their roles in "blocking traffic, damaging public or private property, attacking and injuring people or fabricating and spreading rumours".
Those who did so would receive lighter punishment.
Two suspects had reported to the police by the time the government held a briefing yesterday afternoon.
Choking smog blankets many cities on the mainland and the environmental degradation resulting from the country's breakneck economic growth is angering its increasingly well-educated and affluent population.
Similar protests have succeeded in getting projects elsewhere on the mainland shut down.
The latest demonstrations, which have lasted more than two weeks, turned violent on Saturday with hundreds of police descending on to the streets of Yuhang close to the tourist city of Hangzhou.