At least three workers at a coal mine in central Colombia were killed when an explosion occurred in its galleries, while four of their colleagues are still “missing”, emergency services said Thursday.

Three people were found dead, the local Red Cross said, adding that four other miners were still “missing”.

A previous account, given by the fire department, spoke of four people being rescued and seven stranded in the mine gallery.

The accident happened around 01:00 (local time; 09:00 Greek time) in the municipality of Cukunuba, some 90 kilometers north of the capital Bogota.

Videos uploaded to social media sites showed smoke billowing from the mine and people in plainclothes approaching with flashlights.

According to a self-governing official, Nicolas Garcia, the explosion took place in an underground gallery that connects the El Roble and El Manto mines. It is unclear at this stage whether they were operating legally or illegally.

He clarified that the accident took place in “a zone where permission had been given for mining activity of a traditional type”, but the authorities are still trying to verify if “the conditions of exploitation” were respected.

An ongoing investigation is expected to clarify the causes of the explosion, however, according to the mayor of Cukunuba, Jose Martinez, the initial hypothesis is that it was due to a concentration of gas.

Mining and mining tragedies are common in Colombia, especially in illegally operated mines in Cundinamarca and other central and northeastern provinces.

Authorities counted 1,262 such accidents from 2011 to May 2022. Overall, the country mourns around 100 deaths every year in tragedies of this nature.

Methane concentrations are the most common cause of these accidents in Colombia, Latin America’s largest coal producer.

In mid-March, an explosion at a nearby mine in Soutatoussa municipality killed 21 workers, one of the worst such tragedies in recent years. This area has a long tradition of mining.