A passenger train collided head-on with a freight train in the Czech Republic, killing at least four people and injuring 23 others, officials said early Thursday. 

Interior Minister Vít Rakušan said the crash took place late Wednesday night in the city of Pardubice, some 100 kilometers (62 miles) east of Prague. The high-speed passenger train belonged to the private RegioJet company. 

Transport Minister Martin Kupka said the main track between Prague and the eastern part of the country had to be closed while authorities investigate the collision. 

The state-run train company, Czech Railways, said it's likely the track will remain closed for the entire day "due to the extent of the accident." 

Rescuers said more than 300 passengers were on board the high-speed train heading for the city of Kosice in eastern Slovakia. 

The dead were not immediately identified. 

The corridor in Pardubice, where the trains collided, is vital for Czech Railways. It said the line will also likely be closed tomorrow. 

Prime Minister Petr Fiala called the crash a big tragedy and offered his condolences to the families of those killed. 

-AP