Authorities in Poland say a passenger train has derailed, killing at least one person and injuring more than 50 others.

Officials initially reported that four people had been killed.

The train was traveling between Warsaw and Katowice when it derailed near the town of Baby. The engine and three cars left the tracks, and at least one car tipped on its side. About 280 people were believed to be aboard the train when it derailed.

The cause of the accident was not immediately known.

Rescue teams said the injured were transported to local hospitals. Emergency officials are concerned there may be more injuries because some passengers were thrown through windows and could be pinned under the overturned rail cars.

Passengers reported hearing a loud noise before the accident.