Subway traffic has returned to normal in Moscow after a power-cable fire disrupted the morning rush-hour. City officials said 66 people were given medical treatment, mostly for smoke inhalation. Eleven were hospitalized.
Moscow authorities have begun a probe into Wednesday's subway fire that forced passengers to wait in tunnels for four hours on Wednesday.
More than 4,500 were evacuated after high-voltage cable caught fire, spewing smoke.
Metro spokesman Pavel Sukharnikov said subway cables had emitted smoke before, but on Wednesday the consequences were "more serious."
Large queues built up. Russian television showed dense smoke inside the Okhotny Ryad station, which has exits close to the Kremlin and Bolshoi Theater.
Moscow's subway is an essential link used by up to seven million commuters every day. Streets were thronged by commuters who ended up walking to work.
Some complained of transport paralysis, with replacement buses unable to cope.
Smoke filled carriages
One passenger, identified by the newspaper "Moskovsky Komsolets" as Alexei Suvorov, said his carriage began to fill with smoke while halted in a tunnel between stations.
"After a while, the driver told us to sit on the floor and cover our mouths and noses with wet tissues," said Suvorov.
Passengers emerged smeared with soot and cleaned themselves using water from fire hydrants.
A further short circuit in a cable nearby caused further delay after stations near the Kremlin had initially been reopened.
Sukharnikov said the second section of cable did not burst into flames, because electricity was subsequently turned off.
Moscow's metro system was opened in 1935. It was the scene of deadly suicide bombings in 2004 and 2010 that claimed more than 80 lives.
ipj/dr (AFP, AP, dpa)