An apartment house collapsed Saturday in southwestern Poland, leaving four people dead, four injured and two others missing, authorities said.

Scores of firefighters with dogs were searching the rubble of the building in the town of Swiebodzice (Shvyeh-'boh-tchi-tseh), according to Daniel Mucha, regional spokesman for the firefighters. He said the collapse of two floors of the three-floor building might have been caused by a gas explosion.

Regional governor Pawel Hreniak said the search-and-rescue operation was expected to continue through Sunday.

"I confirm a fourth victim, an elderly man," Hreniak told reporters. "But another resident, an elderly lady, contacted us to say she was away from the house and was fine."

Still, firefighters looking for two more survivors said there were no sounds yet coming from the building's bricks and broken wood.

The governor of Swiebodzice, Bogdan Kozuchowicz, said the pre-World War II building was recently renovated and had been in good technical condition.

The injured were taken to hospitals in Swiebodzice and in Wroclaw. One survivor, identified only by her first name Stanislawa, told TVN24 that she was "miraculously saved."

"I was in the kitchen and suddenly it was dark and full of debris and some broken wooden planks," she said from her hospital bed in Swiebodzice. "I got on top of those planks and started calling 'Help! Help!' Two firefighters came and pulled me out by the arm."

She said her husband was resting on the bed at the time of the collapse.

"I don't know what has happened to him," she said, her voice trembling.

With her teenage son, also a survivor, at her side, she said the family had lost everything.

The head of the medical rescue workers, Wojciech Kopacki, said two of the dead were children.