At least five people have been killed after a series of overnight methane explosions at a coal mine in southern Poland.
The blasts have injured more than 20 others while seven people remain missing, authorities said on Wednesday.
The explosions are reported to have taken place at 00:15 CET around 1,000 metres beneath the surface at the Pniowek mine in Pawlowice.
Rescuers were initially forced to suspend their operation due to a fire, according to the mining company operator Jastrzebska Spolka Weglowa (JSW).
"There were a total of 42 employees in the affected area," the company said on Twitter.
Contact with some of the rescuers has been lost during the operation, mine authorities added.
"At the moment, the area is unsafe for the operation to reach the miners below," Edward Pazdziorko, vice-president of the JSW Group, said on Friday.
Polish Prime Minister Mateusz Morawiecki visited the site of the “tragic occurrence,” and reiterated that the rescue operation was extremely difficult.
Doctors at the Siemianowice Slaskie hospital say that some of those injured are in a life-threatening condition after suffering burns to their lungs and large areas of their bodies.
An investigation into the cause of the explosions is underway.
Poland relies on coal for about 70% of its energy and has experienced other mining accidents in recent years.
In March 2021, two miners died and two others were injured in an accident at the Myslowice-Wesola mine in southern Poland, while five others died at the Zofiowka mine owned by JSW in 2018.