A days-long rescue operation at the world’s largest underground copper mine ended with no survivors after Chilean authorities confirmed Sunday that the body of a fifth missing miner was found following a tunnel collapse.

“Today we finally found (dead) the last of the missing workers,” Aquiles Cubillos, prosecutor for Chile’s O’Higgins region, told reporters.

The collapse occurred Thursday after what officials described as a “seismic event,” prompting the suspension of operations Friday at the El Teniente mining center, which is run by Chile’s state-owned copper giant, Codelco.

Authorities are still investigating whether the seismic activity was triggered by natural causes or mining operations.

El Teniente, located southeast of Santiago, contains more than 4,500 kilometers (2,800 miles) of tunnels and is considered the largest underground copper deposit in the world. The mine produced 356,000 metric tonnes (over 392,000 tons) of copper in 2024—accounting for nearly 7% of Chile’s total output.

Chile’s mining sector is among the safest globally, with a fatality rate of just 0.02% last year, according to the country’s National Geology and Mining Service.