The UK is experiencing major power failures, with trains, airports and traffic lights having all been affected, the BBC reports.
UK Power Networks, which owns the power lines in London, the South East and East of England, said large parts of London and the South East are currently without electricity, saying in a statement: "We believe this is due to a failure on National Grid's network, which is affecting our customers."
Transport for London said the drop in power is affecting traffic lights in the capital, while many train lines are facing delays and cancellations.
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It also tweeted to warn people to be 'very cautious' on the roads.
Blackouts have also been reported across the Midlands, the South West and North East of England, as well as Wales.
King's Cross was badly affected, with hundreds of people stranded as trains were delayed and cancelled during the height of Friday's rush hour.
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The Department for Transport said: "Today's power outage has had knock on impacts on travel.
"We're working hard with Network Rail and others to ensure systems are up and running as quickly as possible, so that everyone can complete their journeys safely."
The National Grid has said the widespread power failures was caused by issues with two power generators. However, the problem has now been resolved.
In a statement, National Grid said: "Even though these events are outside of our control, we have plans in place to respond and the system operated as planned by disconnecting an isolated portion of electricity demand."