Two trains collided near the village of Bialosliwie in west-central Poland, Polish media reported on Thursday.
The website of TVP Poznan reported that two people were injured and 16 fire brigade teams were dispatched to the scene.
Initial reports had said that a passenger train collided with a freight train, but pictures posted on the website of broadcaster TVN24 appeared to show two passenger trains. The pictures showed that some carriages had come off the tracks.
Footage posted on social media showed people standing next to the tracks and derailed carriages.
This is a developing story.