Peru has declared a state of emergency due to heated protests at a copper mine that left four dead on Tuesday, according to The Los Angeles Times.

There are thousands of protesters at the mine, which is in Peru's Apurimac Valley. The mine was scheduled to begin extractions in 2016. In addition to the four who died during Tuesday's bloody confrontation, another 50 protesters and police officers were injured and 21 people were arrested. The government has dispatched 300 more police officers to the mine.

A state of emergency has been declared for 30 days by the Peruvian government, who hopes to conduct talks with protest leaders so that mining operations may go forward as planned. The protesters are worried that the mining project will damage the environment, according to The BBC.

During a state of emergency, police officers do not need a warrant to search private property. The right to freedom of assembly is nullified at this time as well. Peru declared a 60-day state of emergency this past May when protests against a copper mine also resulted in fatalities.

This particular mining project has been in the works since 2009, but repeated delays due to environmental concerns kept it from receiving final approval until 2014, according to UPI.