Four people died and another person was injured in an accident in a southern Polish coal mine on Tuesday, the country's National Office for Mines (WUG) said.
A water pipe burst some 500 metres (1,640 feet) underground at a mine in Jaworzno, killing four people and injuring another, office spokesman Piotr Strzoda told AFP.
A sixth person "escaped unharmed", he added.
A total of 11 people have died in mining accidents in Poland this year, according to the WUG.
Poland had 36 fatal mine accidents last year. The country relies heavily on mining for energy production.