Nineteen miners trapped nearly a kilometer (half a mile) below ground by a cave-in at a copper mine in southern Poland were freed early Wednesday after a seven-hour search.

The men were trapped by fallen rock at the Rudna copper mine in Polkowice after a magnitude-4.7 earthquake struck the area.

"It was a very difficult rescue action," the head of the rescue effort, Grzegorz Wolak, said on the all-news station TVN24. "We did not know if they would live."

A team of 25 rescuers worked through the night to dig their way to the trapped miners, who were luckily all together and in a well-ventilated area when the cave-in occurred, according to Polish media reports.

One of the rescuers, Tomasz Szafirowicz, said that the miners "were very tired but very happy to see us."

"They knew they would return to their families," he said.

One man suffered minor head injuries but all the others are in good shape and were able to return home.