"We experienced issues with two power generators causing loss of power in selected United Kingdom areas" the company is quoted as saying.
As a result, almost 1,000,000 people were affected across large areas of the country.
The problems lasted about 15 minutes before power was fully restored, she added.
The National Grid Electricity System Operator said that the cause of the blackout lies in two failed generators, according to Sky News. It is the electricity distribution network operator for the Midlands, South West and Wales.
Mr Burt said National Grid was "very confident" there was "no malicious intent or cyber attack involved" in the incident.
"Train services running to and from these stations may be cancelled or delayed by up to 60 minutes".
Passengers were filmed forcing their ways through the barriers in an attempt to get themselves on to the first northbound service after services were halted for several hours.More news: Realme to bring 64MP camera tech to India before Diwali
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The drop in power is also affecting travel.
It has vowed to "learn any lessons" from what it described as an "unexpected and unusual event", which saw evening commuters stranded on trains, traffic lights failing and homes plunged into darkness.
Road users were also affected by the power cut as traffic lights were also out of action.
BTP tweeted: "We now have BTP officers assisting at several stations owing to current disruption caused by power issues".
National Grid, which owns the electricity and gas transmission system in England and Wales, said the cause of a major power cut across Britain has now been resolved.
'All trains were stopped while our back-up signalling system started up'. We believe this is due to a failure to National Grid's network, which is affecting our customers. About 300,000 people were affected in London and the southeastern part of the country, while 500,000 people were affected by the Western Power Distribution Network.
Western Power Distribution shared a similar message, and said they are in the process of restoring power to customers.