CODELCO confirmed on Sunday that all five trapped workers at its El Teniente operations have died, as days of intense rescue efforts came away empty-handed after a powerful tremor wrecked the underground mine last week.

The Chilean copper giant confirmed the first fatality on Saturday after discovering the remains of one worker. Three more bodies were found by the search team on Sunday morning. The last body was recovered later in the afternoon.

The workers have been trapped underground since Thursday night, when a 4.2 magnitude earthquake struck the central Chile region and caused the mine to collapse.

One worker was already reported dead at the time of the accident, which occurred in the Andesita section of the mine and is one of the strongest that the El Teniente mine has ever recorded. The latest fatalities bring the total death toll to six.

Rescue operations, which began on Friday with a team of about 100 people, have faced delays due to ongoing aftershocks.

By then end of its rescue efforts, Codelco said the team had only managed to clear 25.5 meters of blocked passages out of 90 meters that it previously said would be necessary to reach the trapped workers.

Mine halted

Immediately following the mine collapse, Chile’s mining minister Aurora Williams announced that the government was suspending all activities at the mine.

Meanwhile, Codelco is investigating whether the deadly incident was caused solely by seismic activity or if mining operations played a role.

After confirming the final death toll, Codelco chairman Maximo Pacheco told the press that the company would convene international experts to investigate the cause and determine “what we did wrong.”

Chile President Gabriel Boric has called for three days of mourning for the miners.

El Teniente, which has been in production since 1905, represents the largest underground copper operation in the world. The massive complex stretches over 4,500 km of tunnels and underground galleries in the Andes Mountains, about 75 km southeast of Chile’s capital, Santiago.

Last year, the mine produced 356,000 metric tonnes of copper, making it one of the top producers globally.