Chinese authorities are vowing to inflict what they call "severe punishment" on organizers of a two-day protest who are concerned about the environmental impact of a proposed heavy metal refinery in their town.
Authorities say unrest broke out Monday when several thousand protesters clashed with police outside a government building in the small central city of Shifang.
Local residents march with banners during a protest along a street in Shifang, Sichuan province, China, July 3, 2012.
Riot police (L) sit next to local residents as they take a rest during a protest in Shifang, Sichuan province, China, July 3, 2012.
Riot police stand in a line to guard a street during a protest in Shifang, Sichuan province, China, July 3, 2012.
Torn up road dividers are placed on a street as roadblocks to prevent police from approaching in Shifang, Sichuan province, China, July 3, 2012.
Local residents gather in front of a municipal government building in Shifang county, Sichuan province, China, in this handout picture taken July 2, 2012.
Local residents parade with banners during a protest along a street in Shifang county, Sichuan province, China, in this handout picture taken on July 2, 2012.
Police responded with tear gas, and pictures circulated online showed police beating protesters. Officials say 13 people were injured.
Shifang police on Tuesday demanded the surrender of those organizing the demonstrations, saying anyone using the Internet or text messages to organize the "illegal protests" should immediately stop their activities.
The Shifang government said Monday it has suspended the construction of the molybdenum and copper refinery, which citizens say would cause heavy amounts of pollution.
Such localized protests are increasingly common in China, where city officials have struggled to balance rapid urban development with rising public anger over environmental threats.
Some information for this report was provided by AFP and Reuters.