WARSAW (Reuters) - Rescuers battled “extremely difficult” conditions on Monday searching for three Polish miners still missing two days after an earthquake, the mine’s operator JSW said.

The quake struck the Borynia-Zofiowka-Jastrzebie coal mine in southern Poland on Saturday morning, trapping seven people almost a kilometer underground. Two of them have been found dead and two others rescued.

“Rescue teams ... are progressing at a pace of several meters per hour. We’re narrowing the area where miners are located,” JSW’s chief executive, Daniel Ozon, told a news conference.

Friends and relatives lit candles at the mine’s entrance, next to a banner reading “Miners of Zofiowka - We Are With You”.

“My husband works here too, that is why my heart goes out to the families ... I would not like to be in their place,” said one woman who only gave her first mane, Malgorzata.

About 250 people were working underground at the time of the quake. The missing miners were from a team drilling a new tunnel.

The 3.5-4.0 magnitude quake was the strongest recorded in the mine, officials there said.

Around 83,000 people work in Poland’s coal mining sector. Last year 15 miners died, and another eight so far this year.