A train packed with passengers derailed in central Poland on Friday as it was travelling from Warsaw to Katowice, killing four passengers and injuring dozens of others.

The train derailed in the village of Baby, near the central city of Piotrkow Trybunalski, with the engine and three of the train's carriages going off the tracks, police spokeswoman Ewa Drozdz said.

Four people were killed and dozens injured aboard the special low-fare train run by the state railway company, PKP. Rescue teams were working at the site, and the cause of the accident was not immediately known, Drozdz added.

A spokesman for PKP, Lukasz Kurpiewski, said some 280 people were believed to be on the train when it derailed around 4:15 p.m. local time.

He said it appeared the train did not hit any obstacle.

A passenger, Marcin Chlebowski, told TVN24 television that the train started to slow suddenly and that he then felt a shock.