ISTANBUL -- An explosion in a coal mine in Turkey's northern Bartin province on Friday killed 22 people, Health Minister Fahrettin Koca said, but it was not clear how many people were still trapped due to the blast that occurred as 110 people were working.

Seventeen others were receiving treatment, Koca said in a statement on Twitter. Earlier, Interior Minister Suleyman Soylu said that at the time of the blast, 49 people had been working 300 meters and 350 metres (985 to 1,148 feet) underground, describing it as the risky zone.

"There are those whom we were able to evacuate from that area. There are those whom we were not able to evacuate from that area," Soylu told reporters at the scene of the blast.

People wait outside the coal mine after an explosion in Amasra in the northern Bartin province, Turkey November 14, 2022. Nilay Meryem Comlek/Depo Photos via Reuters

Energy Minister Fatih Donmez said that the initial indications were that the blast was caused by firedamp, a term referring to methane in coal mines.

There are no ongoing fires inside the mine and the ventilation inside was working properly, Donmez said, adding that there were partial collapses inside the mine.

The explosion occurred 300 metres (985 feet) below the entrance of the mine at around 1515 GMT, the Bartin governor's office said. The mine belongs to the state-owned Turkish Hard Coal Enterprises.

A general view of the coal mine after an explosion in Amasra in the northern Bartin province, Turkey November 14, 2022. Ihlas News Agency (IHA) via Reuters

Footage on Turkish television showed what it said were the families of the miners watching from the sidelines as health and rescue workers huddled around the entrance to the mine. Some miners were taken out and carried off to ambulances on stretchers, footage showed.

Bartin prosecutor's office said it had launched an investigation into the cause of the explosion.

President Tayyip Erdogan said he would go to Bartin on Saturday. "Our hope is that the loss of life will not increase further, that our miners will be saved safely and all our efforts are in this direction," he said on Twitter.