LIMA, Peru (AP) — Peru's government declared a state of emergency in three provinces after three people died and at least 21 suffered injuries Tuesday in a violent protest against a gold mining project that is the South American nation's biggest investment.

It was the second time in five weeks that the government has declared an emergency after anti-mining protests produced fatalities.

Justice Minister Juan Jimenez announced the emergency, which suspends civil liberties, after several thousand protesters attacked a provincial town hall and battled police and soldiers.

Police guarding the municipal building in Celendin, a town in the northern state of Cajamarca, fought back when the protesters attacked and later got help from soldiers, officials said.

Jimenez said two police officers and a solder were wounded by gunfire. Authorities did not say whether police or troops used their weapons.

Three male civilians were killed during the fight, at least two of them by gunshots to the head, Reynaldo Nunez, Cajamarca's health director, told The Associated Press by phone. Most of the injured had received blows, he said.

Nunez said he did not know whether police or soldiers were among the injured.

The local prosecutor said 15 people were arrested.

Celendin is a stronghold of opposition to the proposed $4.8 billion Conga gold mine, which many locals fear will hurt their water supplies. The mine's majority owner is Newmont Mining Co., a U.S. company based in the state of Colorado.

It is one of two main recent flashpoints of opposition against mining in Peru to fall under a government-declared state of emergency. The other is the highlands province of Espinar, near the former Incan capital of Cuzco. The government declared a 30-day state of emergency there on May 29 after two people were killed in a protest against a Swiss-owned copper mine.

In Cajamarca, protesters backed by the regional president, Gregorio Santos, have refused to accept a compromise on Conga proposed by President Ollanta Humala that his government says will protect water supplies.

The compromise includes the construction of four reservoirs to replace reservoirs that are to be destroyed by the project.

Celendin's town manager, Moises Silva, told the AP that violence broke out when construction workers arrived at the town hall and began kicking its main door, prompting police officers to fire tear gas. Continued...