At least eight people have died and five are missing after an underground explosion at a coal mine in central Colombia.

Rescuers are attempting to locate possibly trapped survivors, but as the search drags on, the chances of finding anyone alive seem slim.

It's unclear whether the mine has a license. President Juan Manuel Santos has expressed his condolences to families affected by the tragedy.

Authorities say they believe Friday's explosion was triggered by an accumulation of methane gas. An explosion at a mine in the same town of Cucunuba caused eight deaths in 2008.

Mining accidents are frequent in Colombia, where many facilities operate illegally with poor safety protocols. Through May, 23 miners have died this year compared with 124 in all of 2016.