A Polish mining company on Thursday said at least 10 coal miners had been injured and that rescuers were searching for dozens more.

Some 68 miners were in the affected underground area when an unknown tremor was recorded at about 8 a.m. local time.

What we know so far

Polish Coal Mining Group spokesperson Aleksandra Wysocka-Siembiga said the tremor was at a depth of about 1,200 meters (about 4,000 feet), according to broadcaster Polsat.

"Some of these people are being brought to the surface, some have already been brought up and some have not yet been reached by the rescuers," Wysocka-Siembiga said.

"There are 53 [miners still] underground. The worrying information that we can give is that we do not currently have contact with two workers," she said.

Officials said 15 people had been brought to the surface with some taken to hospital. Air ambulances have been taking part in the operation.

Broadcaster TVT Television tweeted footage from outside the mine, showing emergency vehicles and a rescue helicopter.

Police staff Sergeant Malgorzata Koniarska said officers had received a report of an accident at the Rydultowy mine, some 50 kilometers (just over 30 miles) southwest of the southern city of Katowice.

"A very large number of people are gathering there because families have learned about the quake," said Koniarska. "Our job is to ensure that services can get to the site without obstruction," she added.

What was behind the tremor?

The cause of the tremor was not immediately clear. State Mining Authority official  Zbigniew Rawicki said the quake's epicenter was near where a preparatory excavation is currently being carried out.

However, he stated that "drilling works were not carried out during this shift" and explained that the tremor was during a maintenance and repair shift. 

The European-Mediterranean Seismological Center said the quake had a magnitude of 3.1.

Two miners died in separate accidents in the Rydultowy coal mine in 2019 and 2020. The Rydultowy mine opened in 1792 and currently employs some 2,000 miners. Some of Poland's coal mines are prone to methane gas explosions.

rc/sms (AP, Reuters)