Electricity outages hit large sections of the Russian capital Wednesday, forcing many subway lines and trolleybuses to halt service.
Energy Minister Viktor Khristenko told the Duma, the lower house of parliament, that the cause was a fire and explosion at a substation. He did not immediately give details, and said the incident was under investigation.
Ministry of Emergency Situations spokesman Viktor Beltsov said the outages hit wide areas of Moscow's south. The problems extended as far as the Tula region, about 200 kilometers (120 miles) south of Moscow, Khristenko said.
Officials at the municipal electricity company, Mosenergo, could not immediately be reached for comment. Moscow this week has seen unseasonably high temperatures, meaning electricity demands for air conditioning could have been high.
News reports said the power failure caused some apartment buildings to lose their water supply and forced suspension of trading on Moscow's MICEX stock exchange.
Passengers were being evacuated from stalled subway trains, the Interfax news agency cited system spokesman Dmitri Gaev as saying. Passengers waiting for trains were told to leave the stations.
"Like always, they're not telling us anything," said Lena Trofimova, 44, who was waiting for a bus near the Kremlin after leaving a nearby subway station. Crowds at bus stops in central Moscow appeared larger than usual, but road traffic was moving.
Presidential candidate Ksenia Sobchak, who was accredited for the press conference by Vladimir Putin from Dozhd (Rain) television channel, asked Putin about competition at the coming election