At least 41 people were killed in a coal mine explosion in northern Turkey, President Recep Tayyip Erdogan said Saturday.

"We are greatly saddened as a nation," Erdogan told reporters at the site in the Black Sea province of Bartin.

The blast occurred Friday night at the state-owned Turkish Hard Coal Enterprise's (TTK) mine in the town of Amasra.

A total of 110 miners were working several hundred meters underground at the time of explosion.

Health Minister Fahrettin Koca said 11 workers were being treated in hospital, while 58 others had managed to escape unharmed.

What is known about the explosion?

Energy Minister Fatih Donmez said that initial indications pointed to the explosion being caused by firedamp, a term referring to methane in coal mines. Though he also said the cause of the blast was not yet known for certain.

He said the blast took place at around 6:15 p.m. local time (1515 GMT).

Local prosecutors said they treated the incident as an accident and launched a formal investigation.

A dozen social media users are also under investigation for posts they made related to the mine blast under new "anti-disinformation" legislation. 

Turkey has a bleak record of mine accidents due to weak safety regulations. In 2014, a total of 301 people were killed in a major explosion at a coal mine in the Soma district of the Aegean province of Manisa.

ab, dh/dj (AP, AFP, dpa)