Szczechociny (Poland): Two trains running on the same track collided head-on in southern Poland late on Saturday, leaving 16 people dead and 58 injured, the country's worst train disaster in more than 20 years.

The powerful collision occurred near the town of Szczekociny, just north of Krakow, after one of the trains ended up on the wrong track.

Maintenance work was being done on the tracks in the area, but officials say it's too early to determine the cause of the disaster.

President Bronislaw Komorowski visited the site and said when rescue efforts are over he would make an announcement about a period of national mourning due to the scope of the suffering involved.

Several of the passengers were foreigners, including people from Ukraine, Spain and France, but none of them were among the dead or mostly seriously injured, Prime Minister Donald Tusk said.

"This is our most tragic train disaster in many, many years," he said.

The accident happened on Saturday around 9 p.m. and rescue workers labored through the night to recover bodies and the injured. They brought in heavy equipment to free a body from the mangled wreckage of the train, and ended up finding two, a spokesman for firefighters, Radoslaw Lendor said.

A doctor in one of the hospitals, Szymon Nowak, said many of the injured were in a serious condition, with some in artificially induced comas.

The tragedy was Poland's worst involving trains since 1990, when 16 people were killed in a collision involving two trains in the Warsaw suburb of Ursus. Since then, the most serious Polish rail accident was in 1997, when 12 people were killed in Reptowo.