MOSCOW (AP) -- A rush-hour subway train derailed Tuesday in Moscow, killing 12 people and sending at least 150 others to the hospital, many with serious injuries, Russian emergency officials said.

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

Russian Emergency Situations Ministry Vladimir Puchkov gave the casualty toll at a televised news conference. At least 50 of the injured are in grave condition, the Itar-TASS news agency said, quoting Moscow health department chief Georgy Golukhov.

Golukhov told Russian television that only one person is still trapped in a wrecked train car but said he is still alive.  Emergency services at the scene, however, speculated there could be more trapped commuters. It was not possible to immediately reconcile the reports.

The Russian capital's airports and transit systems have been hit by several terrorist attacks over the past two decades but officials said Tuesday this appeared to be an accident. Puchkov said terrorism is not being considered as a possible cause.

An Associated Press journalist saw injured people being taken out of the Park Pobedy station in west Moscow on stretchers and four medical helicopters taking off from the lawn nearby.

Yuri Akimov, a Moscow spokesman for the emergency services, said outside the station that about 200 people were evacuated from the train, which was stuck between two stations.

Park Pobedy is the deepest metro station in Moscow's subway system _ 84 meters (275 feet) deep, which made the rescue particularly hard. The station serves the vast Park Pobedy, where the World War II museum is located and which is close to Moscow's triumphal arch.

The Moscow Metro is one of the most famous subway systems in the world, known for its palatial interiors with mosaics, chandeliers and marble benches.