Beijing, China ? Twenty-three people were trapped in a flooded coal mine in central China, authorities said today.

The flood swamped the mine in Yuzhou city of Henan province early this morning, trapping 23 people, the State Administration of Coal Mine Safety said in a statement on its Web site. It did not explain what caused the flood.

The official Xinhua News Agency said more than 50 miners were working in the shaft.

The report cited local authorities as saying that many of the workers managed to escape, while a rescue operation was under way to save the trapped workers at the Fushun coal mine.

Xinhua said the mine is owned by the Hebi Coal Industry (Group) Co. Ltd. based in Hebi, a city in Henan. Phone calls to the mine owner and the Yuzhou city coal mine safety bureau rang unanswered today.