At least two protesters were killed and 18 wounded after police opened fire on demonstrators protesting the construction of a $7.4 billion Chinese-owned copper mining project in Peru’s southern province of Cotabambas.

Police and protesters clashed in the mining zone of Las Bambas where Chinese company MMG Ltd. is constructing a mine that could add 400,000 tons of copper to the global supply each year, according to Reuters. Protesters have demanded that MMG change part of its environmental plan and recruit more locals, authorities reportedly said.

"The two men died of bullet wounds. One was age 30, the other age 24," local surgeon Percy Jeronimo said Monday, according to the Associated Press (AP). He added that four others were in critical condition.

About 1,500 police officers and 150 military officers were sent to the area ahead of protests that began Friday. Police reportedly opened fire after demonstrators stormed a part of the mine. Jose Soplopuco, the local health director, told the AP that police also shot at a vehicle carrying doctors, keeping ambulances away from the area.

Interior Minister Jose Luis Perez said fundamentalists from outside the mining area had instigated the protests. "Police used non-lethal weapons at the start, and then, to defend themselves, had to use lethal weapons," Perez reportedly said, in a televised interview.

Peru is the world's third largest copper producer and mining comprises about 60 percent of the country’s export earnings.