According to Reuters, none of the workers in the explosion at the Abid Lolic operation, which employs a total of 276, sustained life-threatening injuries.

“The cause of the accident is still unknown,” regional police spokesman Rusmir Prohan told the news service, adding that an investigation by mine inspectors and local authorities was forthcoming.

Local media reported that the event could have been tied to methane, as some workers were being treated for gas poisoning as well as burns.

Abid Lolic produces coal for Bosnia’s largest power generator, EPBiH.