Suspected methane blasts have killed at least five people and injured 20 others in a coal mine in southern Poland, authorities said Wednesday.

Mining company JSW said 13 teams were involved in a rescue operation to find several workers who are still missing. However, efforts had to be put on hold due to a second explosion and subsequent fire as well as difficult conditions underground.

JSW said the explosions occurred at its Pniowek mine in Pawlowice shortly after midnight at a depth of 1,000 meters (3,281 feet).

There were 42 miners in the area at the time. Several of the initial rescuers were also trapped. Experts were evaluating the possibility of restarting rescue operations.

Polish PM mourns ‘tragedy’

“A tragedy happened here today,” Polish Prime Minister Mateusz Morawiecki told reporters during a visit to the scene. “The words catch in one’s throat because we now know that five people are dead and seven are still trapped inside the mine galleries.”

“There are also more than 20 people in the hospital with severe burns,” he added.

Doctors at the Siemianowice Slaskie hospital said some of the victims were suffering life-threatening burns to their lungs and large parts of their bodies.

Rescue workers were among the victims, Morawiecki said.

Poland, which relies on coal for most of its power, has experienced several other mining accidents in recent years.

Warsaw has announced it is attempting to end coal imports from Russia following the invasion of Ukraine.

ab, nm/rc (AFP, AP, dpa)