BOGOTA, Colombia (AP) — An explosion in a coal mine in central Colombia killed nine miners and injured six others who were recovering in a hospital Tuesday, officials said.

There were 15 miners inside the Carbonera Los Pinos mine in Sutatausa, about 50 miles (80 kilometers) north of Bogota, when the explosion occurred Monday, Cundinamarca provincial Gov. Jorge Emilio Rey said on X.

Three of the miners escaped on their own, and the remaining three survivors were rescued.

Colombia’s National Agency for Mining said in a statement that officials inspected the mine in early April and had recommended sealing off areas no longer being used for coal extraction, because of a potentially dangerous “accumulation of gases including methane.” The agency didn’t say whether the recommendation was implemented.

The agency expressed its solidarity with families of the victims and said it “regrets this accident in which, thanks to the opportune action of rescue workers, six miners were saved.”

Mining accidents are common in central Colombia, where dozens of small operators run coal and emerald mines.

In 2023, 11 miners were killed by an explosion at another coal mine in Sutatausa. In 2020, 11 miners died during a mining accident in Cucunuba, another municipality in Cundinamarca province.