A section of the Moscow underground collapsed onto a metro train this morning causing an evacuation and major disruption to the system.
A government official said all passengers had been evacuated and confirmed that there were no casualties.
"There are two groups of workers down in the tunnel and they are clearing up the rubble, and cutting through the reinforced concrete," Viktor Beltsov said.
Emergency services said a section of concrete had fallen from the tunnel roof as a train was travelling between stations north of central Moscow and pierced one of the carriages.
Officials had said the affected carriage caught fire but Russian news agencies, citing other officials, later said there had been no fire.
The accident happened on the Zamoskvoretskaya line, about six kilometers north of Moscow 's city centre. The train was travelling between the Voikovskaya and Sokol stations, heading south.
Russian news agencies quoted emergency services as saying they were investigating whether building work on the surface had caused the tunnel to give way.