A Look Inside Russia Subway Station Following Derailment

— -- A rush-hour subway train derailed in Moscow today, killing at least 20 people and injuring more than 160 others, authorities said.

Several cars left the track in the tunnel after a power surge triggered an alarm, which caused the train to stop abruptly.

The scene was chaotic, featuring cars piled upon other cars, twisted metal and smoke. More than 1,100 people were evacuated from the tunnel where the derailment occurred.

The station where the crash occurred is one of the deepest in the subway system, making rescue efforts more challenging.

Emergency crews could be seen carrying injured travelers on stretchers up the subway steps, loading them into ambulances and helicopters.

Some passengers remained trapped hours after the derailment.

Wednesday has been declared a day of mourning in Moscow.

There are no reports of terrorism, authorities said.

The Associated Press contributed to this report.