(Details added - first version posted at 11:53)
10 people have been killed and 120 injured as several subway cars derailed on the Moscow Metro on the Arbatsko-Pokrovskaya dark blue Metro line on Tuesday morning, RT reported.
"The number of the dead is 10," said Pyotr Biryukov, deputy mayor of Moscow, as cited by ITAR-TASS.
"One hundred and twenty people have sought medical help, 106 were taken to hospital. About a half of them are seriously injured," Golukhov told ITAR-TASS.
The first carriage of the train sustained most of the damage, according to an eyewitness of the accident who spoke to RT. Ivan, said he was in the second car when the train suddenly braked and the lights went off.
"I was tossed up in the air," the young man says. "There was blood on the floor, heads bruised, arms broken. Panic broke out."
Ivan also says after the train derailed there was a flash and then the tunnel was filled with thick smoke.
"The car was badly damaged. We started to get out. We saw a door in the tunnel's wall. Men eventually broke that door and we saw workers, constructing a parallel tunnel. They helped us to get out."
Another eyewitness, who spoke to LifeNews, was in the fifth carriage and says they had to wait for 30 minutes before the evacuation started.
"So as we got out, we proceeded to march on foot, probably for two or three minutes - along the tunnel with cables underneath. The train driver had told us right away to stick to the right side, so we did. No sooner had we got to the surface than we realized it was a full-blown emergency."
Law enforcement officials told that three train cars had derailed, "but not overturned."
Moscow authorities do not consider the cause the accident in the Metro could have been a terrorist act, according to Maksim Liskutov, the head of the transport department in the Moscow government, cited by Dozhd TV channel.
About seven people reportedly remain trapped in one of the train carriages.
Attempts are being made to try and evacuate the stricken passengers, who are stuck in a tunnel between Park Pobedy and Slavyansky Bulvar stations, in the west of Moscow.
There are some seriously injured people, according to preliminary reports. Doctors and rescue workers have deployed stretchers down the tunnel for their evacuation.
News of the derailment was preceded by reports of smoke detected on the dark blue line of the Moscow Metro. Later, Moscow's emergencies agency denied reports of smoke and said a sudden failure in the electricity supply to a conductor rail could have caused the accident.
Moscow's emergencies agency press service says the train derailed because it had to brake too suddenly.
"At 8:39am Moscow time [04:39 GMT] on a stretch between stations of Park Pobedy [Victory Park] and Slavyansky Bulvar there was abrupt deceleration of a train," a press service employee told RT.
Sixty-six buses, forty ambulances and eight helicopters have been deployed by rescuers for evacuations. Fifty people have already reportedly been evacuated from Slavyansky Bulvar and 200 from Park Pobedy.