(CNN) -- Anti-mining protesters stormed a government building in northern Peru on Tuesday, leaving three people dead and more than 20 wounded, the Interior Ministry reported.
Among the victims were soldiers, police officers and a 17-year-old, it said. Sixteen people were detained.
The violence took place in Celendin, a town in the northern region of Cajamarca.
"These events are the reprehensible consequence of the violence encouraged by some leaders, who must now take responsibility," said Interior Minister Wilver Calle Giron.
Protesters are upset over the development of a nearly $5 billion gold mining project called Conga, which is operated by the U.S.-based Newmont Mining Corp.
They say the project will have a negative impact on local water supplies and harm the area's ecosystem.
For its part, Newmont has said construction will move forward only if it can be done in a safe and responsible manner.
In a statement last month, the company vowed to first build water reservoirs, before mining facilities.
"The reservoirs will supply water to downstream users who currently only have water flowing during the rainy season. This confirms the respect the Company has for Cajamarca and its people," it said.
Clashes over mining projects are common in Peru, a major metals producer.
In May, the government declared a 30-day state of emergency in the southern region of Espinar after violent anti-mining protests left two civilians dead and at least 76 police officers injured.
In December, a state of emergency was declared in parts of Cajamarca after weeks of protests against the Conga project.