At least 20 people were killed and more than 120 were injured when a Moscow underground train derailed during the morning rush hour in one of the worst accidents on the Russian capital’s subway system in years.

President Vladimir Putin, who is away in Brazil, ordered a criminal investigation into the accident, which is likely to raise further questions over Russia’s transport safety record. There was no suspicion of a militant attack – the cause of scores of deaths in Moscow’s subway system in years past.

Three carriages derailed on a train travelling between two stations at 70 km per hour at around 8.35 am (0435 GMT) on the world’s busiest subway system.

“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. Many people were hurt, mostly in the first rail car because the cars ran into each other.”

Rescue workers evacuated more than 1,000 people from the area of the accident, the Emergencies Ministry said. Injured passengers were carried on stretchers, bloodied and bandaged, out of both metro stations.

Helicopters ferried the most seriously hurt to hospital and passengers helped to the surface by emergency services looked stunned or were crying.

“There is no one alive left,” Moscow deputy mayor Peter Biryukov said. “The cause is not known, the work continues.”

Some bodies were recovered from the wreckage but others remained underground, crushed in the accident, he said.

The Investigative Committee put the toll at 20 dead. Russian news agency Itar-Tass quoted Health Ministry representative Oleg Salagai as saying that 129 people were injured, 42 of whom were in a serious condition.