At least 50 of those injured are in grave condition, health officials told the AP.
Over 1,100 people were evacuated from the train, which was stuck between two stations, in a seven-hour rescue mission.
By late Tuesday afternoon, rescuers had recovered seven bodies and were working to recover 12 more that were trapped in two collapsed train cars, said Alexander Gavrilov, deputy chief of Moscow’s emergency services.
One woman who was taken from the scene died shortly after at a Moscow hospital.
It is still unclear what caused the train to derail.
According to a Vladimir Markin, a spokesman for Russia’s top investigative body, there may have been a fault in one of the cars. He said that earlier reports that a power surge triggered an alarm that caused the train to stop suddenly were incorrect.
One survivor of the accident told Rossiya 24 television outside the metro station that he felt “a jolt” before the train suddenly stopped.
“There was smoke and we were trapped inside,” he said. “It’s a miracle we got out. I thought it was the end.”
While technical errors are a frequent problem in the Moscow Metro, there has not been a deadly accident in decades.
There have been 13 emergency incidents on Moscow’s metro system so far this year but no one was injured in the earlier incidents, according to ITAR-TASS.
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