The death toll from an explosion at a series of connected coal mines in central Colombia has risen to 21, President Gustavo Petro says, after large-scale rescue efforts to free 10 miners who were trapped underground had failed.

“Despite all the efforts of the rescue teams, unfortunately 21 people lost their lives in this tragic accident in Sutatausa,” a town 74km (46 miles) north of the capital, Bogota, Petro said in a tweet on Thursday morning.

“All my solidarity to their families,” the president wrote.

A day earlier, Cundinamarca Governor Nicolas Garcia told Blu Radio that at least 11 miners had died in the blast, which occurred late on Tuesday due to an accumulation of gases that exploded after a worker’s tool caused a spark. It spread through the connected, legal mines.

Nine miners were able to escape, but 10 were trapped 700 to 900 metres (2,300 to 3,000 feet) underground, Garcia told reporters on Wednesday.

More than 100 rescue workers were deployed to free them.

“My thanks to … each and every one of the rescuers who during these two days gave themselves body and soul to the rescue work in Sutatausa,” Garcia wrote on Twitter on Thursday morning.

“Our hearts are broken,” he said.

People wait during the search and rescue work following an explosion of a mine in Sutatausa, Colombia, March 15, 2023

Colombia is home to numerous open and underground gold and coal mines. Explosions and other incidents frequently occur, mostly at operations that are illegal or do not adopt sufficient safety measures.

The South American nation has reported 1,260 mining incidents from 2011 to May 2022 and an annual average of 103 deaths, according to official figures. In 2021, 148 deaths were recorded.

The most serious recent incident occurred in June 2010 when 73 people were killed in a mine explosion in the northwest.

In August, nine miners were rescued from a collapsed illegal coal mine in Cundinamarca.

On Thursday, Colombia’s president said, “Each work fatality is not only a business failure but also a social and governmental one.”