Five people were killed and nearly 100 were injured when an Moscow underground train went off the rails between two stations during the morning rush hour on Tuesday, the Health Ministry said.

Injured passengers were carried on stretchers out of metro stations and helicopters ferried the most seriously hurt to hospital. Some of the passengers looked stunned after being helped to the surface by emergency services.

A spokesman for the Emergencies Ministry said a power surge caused the train to stall and several cars to derail between the Slaviansky Boulevard and Park Pobedy stations.

"It braked very hard. The lights went off and there was lots of smoke," a man, his nose bloodied, told Rossiya-24 television.

"We were trapped and only got out by some miracle. I thought it was the end. Many people were hurt, mostly in the first rail car because the cars ran into each other."

Russian news agencies reported earlier on Tuesday that 20 people had been trapped in one of the damaged rail cars. There was no talk of foul play. - Reuters