Russian authorities say power has been fully restored to the Moscow region Thursday, a day after a massive blackout knocked out electricity to large parts of the Russian capital. 

The blackout Wednesday left thousands of people stranded on subways, shut down the stock market, and forced hospitals to switch to emergency power. 

Energy Minister Viktor Khristenko blamed the power outage on a fire and explosion at an energy substation.

President Vladimir Putin has accused the state-run power company (Unified Energy Systems) of negligence.

Meanwhile, prosecutors have opened a criminal case over the power outage, and say they plan to question the chairman of the power company, Anatoly Chubais, who is also one of Mr. Putin's top political rivals.

The outage extended as far south as the Tula region, about 200 kilometers south of Moscow.