A power outage put a large swath of the U.K. in the dark during hectic rush hour period on Friday, according to recent reports and a tweet from the UK Power Network: "We're aware of a power cut affecting a large area of London and South East," network officials tweeted. They said the outage was pegged to generator failures at U.K.-based National Grid /zigman2/quotes/208805676/delayed UK:NG +0.80% . Bloomberg News reported that outage has led " disruption on multiple rail lines out of the capital, including the Gatwick Express." Some reports indicate that power was slowly being restored in many areas. The U.K.'s Express on its website reported that British Transport Police sent officers to train stations to provide assistance to stranded travelers.