The transit service on a section of the Moscow metro's Green Line has been interrupted after a tunnel was damaged between two stations.
The incident happened at about 3:30 p.m. when a concrete pile pierced through the tunnel walls between the Avtozavodskaya and Kolomenskaya stations, a spokesman for Moscow's transport department said.
Service between the Avtozavodskaya and Kashirskaya stations has been halted.
Nobody was injured as a result of the incident, Interfax reported.
Andrei Bochkarev, head of construction in Moscow, said he hopes normal service will resume on the Green Line by the end of the day, RIA Novosti reported.
The pile has already been removed and repair work is being carried out, Bochkarev said.
Moscow's transport department said it will carry out an investigation in the incident.
The city's building regulator said that the work was "unsanctioned" and was being carried out on a piece of land owned by Russian Railway on Kozhukovsky Proezd.
Passengers have been advised to use alternative routes or use free buses provided by the city, while motorists have been told to steer clear of the areas affected by the accident.