A rush-hour power cut has caused major disruption on rail and Tube services in London and the South East.
Some Tube stations were evacuated
Power returned to the system at about 1900 BST and the rail and tube network took several hours before most services resumed normal operations.
Network Rail said about 1,800 trains were affected by the power cut, caused by a fault with the National Grid.
Train company Connex reported the power went out between London and Ashford, in Kent.
South London was hardest hit and Transport for London said 60% of the Tube network was affected.
Stations and trains were evacuated as commuters using the Tube were plunged into darkness and some were stuck underground as the power went off at about 1820 BST.
Buses quickly became extremely busy and lines of people waiting for taxis grew as commuters abandoned packed Tube platforms.
London Fire Brigade took 400 calls and say they rescued about 100 people who were stuck in lifts.
Mayor of London Ken Livingstone said at least 250,000 people were affected and said the situation showed the need for a serious look at the National Grid and why power went down for so long.
"We've never had this catastrophic failure before and we clearly can't have it again," he said.
British Transport Police say Tube services have been restored.
Commuter Jane Marriott, 27, was trying to get to Paddington from Canada Water on the Tube, but ended up taking the bus and walking part of the way.
She said: "It's absolute chaos, it's very wet which is making people very miserable.
"A bit of the Blitz spirit is kicking in and people are talking to each other which is nice, but we need more cabs and more bus lanes."
Queues grew for buses and taxis
Businesses and homes in Brixton, Battersea and London Bridge were plunged into darkness and police said 270 sets of traffic lights went out.
St Thomas's Hospital, in south-east London was among those which had to rely on back-up power generators.
Network Rail spokesman Kevin Groves said the situation was "unprecedented" as far as he knew.
'Very similar to New York'
The National Grid is investigating the cause of the fault but spokesman Sean Regan said any loss of power supply was "an unusual occurrence".
He added: "There was a fault in the 275,000 volt system affecting a ring around London, which occurred at 1826 BST.
"Power to the distribution network in London was restored at 1900 BST.
"Obviously it is going to take the regional distribution network some time to
restore supplies to the end users of their system. Hopefully it shouldn't be
Civil servant Alan Basford, 52, from Meopham, Kent, added: "This disruption
seems very similar to what happened in New York, and it's also a bit strange the two events have happened close together."