Alexander Gavrilov, deputy chief of the Moscow emergency services, said rescuers have recovered seven bodies and are working to extract 12 more from two wrecked train cars.
Moscow’s transit system has been previously targeted by terrorists but this time Russian officials have vehemently dismissed terrorism as a possible cause.
Yuri Akimov, a Moscow spokesman for the emergency services, said outside the Park Pobedy station in west Moscow that about 200 people were taken from the train, which was stuck between two stations.
Park Pobedy is the deepest metro station in Moscow’s subway system – 275ft deep, which made the rescue particularly hard. The station serves the vast Park Pobedy, where the Second World War museum is located.
Injured people were being taken out of the Park Pobedy station on stretchers.
Paramedics carried one woman covered with a blanket to the lawn by the famous Triumphal Arch and put her on a medical helicopter, one of four seen taking off from the park.
In the scorching summer weather authorities provided drinking water to survivors, some of whom were sitting nearby the station’s entrance in a state of a shock.
Photos on social media showed passengers walking along the tracks inside the dimly-lit tunnel.
A man with a bloody cut on his brow told Rossiya 24 television that he felt a jolt and the train abruptly came to a halt.
“There was smoke and we were trapped inside,” he said. “It’s a miracle we got out. I thought it was the end.