Up to 50 hurt in Moscow subway accident - Interfax
"We have information from witnesses that the train braked suddenly as a result of which several cars were derailed," a spokesman for the emergency ministry told Reuters.
At least two people were in a serious condition and were being taken to hospital by helicopter, Russian television said.
(Reporting by Tatiana Ustinova, Writing by Alissa de Carbonnel, Editing by Timothy Heritage)