Six people were killed and several dozen injured after parts of a freight train derailed and collided with a passenger train south of Moscow, Russian officials said.
Seventeen people suffered serious injuries including one child, the Russian health ministry said.
A ministry official said the accident occurred at around 12.30pm local time (9.30am Irish time) between the towns of Bekasovo and Naro-Fominsk, about 80km southwest of Moscow.
The passenger train had been travelling from the Russian capital to Moldova's capital Chisinau.
Five people died in the immediate aftermath of the accident and another died later in hospital, officials said.
The health ministry said this evening that a total of 25 were hospitalised.
The emergencies ministry said there were about 400 passengers on the train.
Four of those who died and 13 of those hospitalised had been identified as Moldovan citizens, Moldova's emergency ministry said.
A picture released by the emergencies ministry showed one side of the passenger train completely torn away, with passengers emerging from the wreckage.
At least 500 people were involved in rescue efforts, officials said, and seven helicopters were used to ferry the injured to hospitals.
Russian Railways said in a statement that 15 wagons of the freight train had derailed, damaging at least two carriages of the passenger train.
The cause of the accident was not immediately known.
Investigators were on site and officials said a criminal investigation had been launched.