Four people were killed and many more injured when a passenger train collided with a freight train in the Czech city of Pardubice, a spokeswoman for the rescue service told state television early on Thursday.
A spokesman for the railway fire brigade said dozens of people were injured in the accident overnight, with some sustaining serious injuries.
Large numbers of firefighters, paramedics and doctors as well as at least one rescue helicopter have been deployed to the scene of the accident, some 100 kilometres east of Prague.
Images showed the carriage located right behind the passenger train's locomotive had derailed and was badly damaged.
The affected train was a night express operated by private railway company Regiojet and had been enroute from Prague to Kosice in Slovakia.
Czech Interior Minister Vit Rakusan and Transport Minister Martin Kupka are on their way to visit the accident site, Rakusan said on X.