A scuffle broke out in eastern Kyrgyzstan on Monday between hundreds of angry local residents and Chinese construction workers at a gold mine operated by a Chinese corporation.

The locals believe the gold mine has contaminated the soil and killed their livestock. Kyrgyzstan authorities said they have tested the soil and found it safe.

Radio Free Europe reported on Tuesday that about 500 locals descended on the mine, forced their way into the construction site, injured 20 of the Chinese construction workers they found, and seized several of the mining company’s trucks. 

A number of the demonstrators were also injured in the fight, during which “both sides threw stones at each other,” according to the Kyrgyzstan health ministry.

“Deputy Prime Minister Kubatbek Boronov and Interior Minister Kashkar Junushaliev have arrived at the site and have called on the local residents to disperse. However, the residents said they will start removing the company’s equipment from the area themselves if the authorities do not do so,” RFE said.

AFP noted villagers in the former Soviet country have long complained about mining operations damaging the environment and interfering with their way of life. Kyrgyzstan is among the poorest of the former Soviet states and relies heavily on income from the mines, which are generally leased to foreign operators. Uranium mining is an especially contentious issue. Government officials often tell protesters that under existing national law, it is very difficult to revoke mining licenses unless the most egregious offenses are committed.

China’s Zhong Ji Mining company obtained a license to work the Solton Sary gold field in 2012. Local villagers began complaining last month that Zhong Ji Mining’s activities have poisoned the soil, despite reassurances from their government that no contaminants have been found.