According to local media outlets, including Colombia Reports, Hernan Alfonso Barrera Pena and John Freddy Ordonez Trivino were trapped when part of a tunnel collapsed at the La Esperanza coal mine in the country’s northeast region.

The workers are about 180 feet below the surface, and Thursday’s explosion is slowing efforts by engineers to create a parallel tunnel system to reach the area where they are believed to be trapped.

“We are working with a team of mining engineers 24 hours at the La Esperanza mine,” Sogamoso Civil Defense director Corone Luis Fernando Pineros told the news service.

Tasco Mayor Javier Manrique told press that the Red Cross was providing assistance with the rescue.

“There is hope they are alive,” he said.

The incident followed an explosion earlier this month at another Colombian mine that reportedly took the lives of several workers.

While some media outlets reported five dead, regional disaster chief Luis Alfonso Tarazona told the Associated Press that six miners were killed at the San Roque operation in Sardinata, in the state of Norte Santander.

The names of the workers were not released.

According to Xinhua, Colombian officials investigating cause are citing an accumulation of gas while eight miners were working an estimated 800 meters underground.

The South American country has recorded 73 mining deaths so far this year, all from the San Fernando blast in the northwestern state of Antioquia in June.