A Moscow subway train derailed during the Tuesday morning commute, killing at least 20 people and sending 150 others to the hospital, according to a Fox News report.

Of the 150 sent to the hospital, at least 50 were listed in critical condition.

Rescue crews by late Tuesday afternoon have pulled seven bodies out of the wreckage of the two subway trains and were working on locating 12 more bodies, said Alexander Gavrilov, deputy chief of Moscow's emergency services. A woman that was taken from the scene died at the hospital.

Despite the casualties, more than 1,100 people were safely removed from the train in a seven-hour rescue effort. Photos posted to social media websites in Russia showed evacuated passengers walking along the tracks in the subway tunnels.

The train cars became derailed when a power surge engaged an emergency alarm, which caused the train to stop suddenly. The abrupt halt forced the trains to coil and take up the entire width of the subway tunnel.

The train came off the tracks between Slaviansky Boulevard and Park Pobedy stations in the west of the city, BBC reported. Park Pobedy is 275-feet deep, making the rescue efforts even more difficult.

"The train slowed down abruptly, the lights went off, and then there was a spark of fire and smoke. We were blocked in," one passenger told Russian TV.

Another told Reuters: "We were trapped and only got out by some miracle. I thought it was the end. Many people were hurt, mostly in the front carriage because the cars ran into each other."

Moscow's Metro is among the world's most famous subway systems, noted for the intricate designs of its stations. Accidents on the metro aren't a novelty, but rarely do people get hurt. Tuesday's accident is believed to be one of the worst in the city's history.