The locomotive and six passenger carriages flew off the tracks and were left a mass of twisted metal when a Polish long-distance train rammed into a bridge some 210 miles (340 km) from Prague.
Sixteen fire brigade units were sent to the crash scene
The train was carrying some 400 passengers -- many of them young music lovers en route to a festival in the Czech town of Pardubice.
Lukas Humpl, spokesman for the local rescue service, said rescue crews were scrambling to help victims at the scene.
Train going from Krakow to Prague
The international train was en route from the Polish city of Krakow to Prague, police spokeswoman Miroslavva Michalkova-Salkova told AFP news service.
"It's horrible," she said. "It's a disaster. All the rescue services have been mobilized."
The number of deaths has yet to be certified, with some reports saying 10 people have died.
Sixteen fire brigade units with 30 vehicles had been sent to the scene, along with ambulances and helicopters to ferry the injured to local hospitals.
"We have conducted a search of the site," fire service spokesman Petr Kudela told the dpa news agency. "We hope no-one else is there
A Czech railways spokesman said the train was travelling at 140 kilometers an hour (about 87 miles per hour) when it hit part of a road bridge which had fallen on to the track.
Cause of accident still unclear
"It probably hit part of a motorway bridge under construction which fell on to the track," said the spokesman Jan Kucera.
The locomotive and three passenger carriages were derailed. "There's a lot of damage," he said.
However, a fire brigade spokesman quoted by the Czech national television CT said the bridge collapsed on to the leading carriages of the train as it was passing underneath, AFP reported.