MOSCOW — A subway train derailed Tuesday deep below Moscow’s streets, twisting and mangling crowded rail cars at the height of the morning rush hour. At least 21 people were killed, Russian officials said, and 136 were hospitalized, many with serious injuries.
The Russian capital’s airports and transit systems have been a prime target for terrorists over the past two decades, but multiple officials vigorously dismissed terrorism as a possible cause.
The Moscow Metro is world-famous for its palatial interiors with mosaics, chandeliers, and marble benches. Park Pobedy, where the derailment occurred, is Moscow’s deepest metro station — 275 feet below the surface — which made the rescue particularly difficult. The station serves the vast park where Russia’s World War II museum is located.
It was unclear what caused the train to derail. Lines of inquiry included a fault in one of the cars or the sinking of the roadbed, according to Vladimir Markin, spokesman for Russia’s top investigative body.
Of the 136 people hospitalized, at least 42 were in grave condition, health officials said.
Over 1,100 people were evacuated from the train, which was stuck between two stations, in a rescue operation that ended more than 12 hours after the accident.
In video released by the Emergency Situations Ministry, several wrecked train cars looked almost coiled, occupying the entire width of the tunnel. Workers were trying to force open the mangled doors of one car to retrieve bodies. Photos posted on social media sites showed passengers walking along the tracks in the dimly lit tunnel.
Russian officials rushed to open an investigation into the accident. President Vladimir Putin, who is traveling in Brazil, demanded a detailed investigation into the ‘‘reasons for the event’’ and asked the country’s top investigators to open a criminal case, his spokesman told Russian news agencies.
Mayor Sergei Sobyanin also told reporters that unnamed officials will not only be fired but also charged with crimes, though he would not say what charges they might face. Prime Minister Dmitry Medvedev offered his condolences for the victims and their families.
Dozens of injured people were carried out of the station on stretchers. Several survivors sat on the sidewalk near the station’s entrance in an apparent state of shock.
Witnesses told Rossiya 24 television that they felt a sharp impact that knocked them off their feet and hurled them across the train cars.
‘‘Everybody spun to one side,’’ said one witness. ‘‘There was a sharp brake, and smoke was in the air. People couldn’t leave for a long time. The way was blocked.’’
While technical glitches are regular occurrences in the Moscow Metro, the subway hasn’t seen deadly accidents in decades.
Terrorism is another matter. More than 100 people have been killed in bombings on Moscow’s subway trains or near stations since 2000.