by Maria Ogryzlo and Biodun Iginla, BBC News

A passenger train has crashed in central Poland, killing at least four passengers and injuring more than 20, rescue officials say.

The inter-city train from Warsaw to Katowice was derailed at the village of Baby, near the city of Piotrkow Trybunalski, emergency services said.

The engine and three of the carriages went off the tracks. It was not clear what caused the derailment.

Police spokeswoman Ewa Drozdz said rescue teams were working at the site.

"We heard a huge noise," passenger Marcin Chlebowski told Poland's TVN24 news channel.

"The first wagon was completely destroyed, windows smashed and its sides smashed. People remained calm - many were in shock - and rescue crews arrived rapidly."

The first carriage was reported to be lying on its side.

Polish PKP railways spokesman Lukasz Kurpiewski told TVN24 that about 280 passengers were believed to be on board the train.