At least 16 people were injured on Monday when an explosion derailed several carriages of a passenger train travelling between Moscow and St Petersburg, officials and media said.
"As a result of an explosion ... several carriages from passenger train No 166 came off the rails," Russian Railways said in a statement, according to news agency RIA.
It was not immediately clear what caused the explosion.
An Emergencies Ministry spokesman said there was no news of fatalities.
"The latest information we have is that 16 people were injured," spokesman Viktor Beltsov said by telephone. "Four carriages came of the rails."
Russia has closed the main train line between Moscow and St Petersburg, the country's second city, news agencies reported.
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