A lightning strike that damaged a key power station caused a mass power cut Friday in Baku and other parts of Azerbaijan, halting the capital's metro and creating traffic chaos for several hours, officials said.

Lightning hit the power plant at Mingacevir in northwestern Azerbaijan during a storm overnight, disabling several power units which were burned, the emergencies ministry said in a statement.

"Due to extremely unstable weather coupled with heavy rain, a lightning strike caused a fire" at the power station, state power company Azernergy said in a statement.

There was no electricity in Baku as the capital woke up in the dark while the metro stopped working. Traffic lights also were not working in several places, causing huge traffic jams. However, the city's airport was not affected.

Power was restored after just over three hours and the fire was extinguished, the Azenergy statement said.

The Baku metro press service also said that the underground rail system was running again.

There were no reports of any casualties as a result of the lightning strike at the coal and fuel-fired power station, which reportedly supplies almost half of the country's electricity needs.