ANKARA, Turkey (AP) — An explosion inside a coal mine in northern Turkey killed at least 22 people, Turkey’s health minister announced, while rescuers were trying to bring dozens of others trapped inside the mine to the surface.

The explosion occurred 6:45 pm at the state-owned TTK Amasra Muessese Mudurlugu mine in the town of Amasra, in the Black Sea coastal province of Bartin.

Energy Minister Fatih Donmez said a preliminary assessment indicated the explosion was likely caused by firedamp — a reference to flammable gases found in coal mines.

There were 110 people in the mine at the time of the explosion, Interior Minister Suleyman Soylu, who traveled to Amasra to coordinate the rescue operation, told reporters. Most of the workers were able to evacuate following the blast, but 49 were trapped in a higher risk area of the facility, the minister said.

Soylu would not provide a number for those still trapped, saying some among the 49 had been lifted to safety.

Health Minister Fahrettin Koca announced on Twitter that 22 people were killed in the blast. He did not say how many people were taken out of the mine with injuries, but said eight were in serious condition.

Several rescue teams were dispatched to the area, including from neighboring provinces, Turkey’s disaster management agency, AFAD, said.

President Recep Tayyip Erdogan announced he was canceling a planned visit to the southeastern city of Diyarbakir and would travel to Amasra instead to coordinate the rescue operation.

The private DHA news agency quoted one worker as telling Bartin Governor Nurtac Arslan that he came out of the mine by his own means. He described feeling a “pressure” but said he could not see anything due to the dust and dirt.

People rushed to the mine for news of trapped friends or colleagues, DHA reported.

In Turkey’s worst mine disaster, a total of 301 people died in 2014 in a fire inside a coal mine in the town of Soma, in western Turkey.