A rail company today announced it will review its response to massive disruption to services after thousands of passengers were stranded for hours and a heavily pregnant woman joined a group who got off a train and walked along tracks.
South West Trains (SWT) said the problems last night on services into and out of London Waterloo were caused by deliberate damage to signalling system cable.
Scores of trains ground to a halt, some without power, throughout last night, with services only resuming late in the evening.
It is understood that Emma Firth, who is eight months pregnant, was threatened with arrest by one police officer after she joined a group of passengers who took matters into their own hands and got off a train outside Woking in Surrey.
Many passengers decided to jump off trains using emergency exits and walk down the track, leading to power being turned off.
Passengers vented their anger today on social network sites, saying that station staff were a "disgrace" and accusing SWT of leaving passengers stranded for hours on trains with no ventilation, food or water.
One man said he was threatened with arrest after "raising his voice" to a member of staff, while drivers were said to be stranded on trains, worsening the chaos.
One passenger tweeted: "SWT locks passengers on train for five hours with no food, light, air, water, threatens arrest if escape attempted."
Another said: "Major questions over incident management", while others said SWT should be forced to reconsider its approach to such incidents to avoid passengers being stranded.
A South West Trains spokesman said: "We are very sorry for the significant impact last night's signal problems had on a large number of our passengers. We would like to thank them for their patience during some extremely difficult circumstances.
"We appreciate that many passengers spent several hours on trains while Network Rail engineers worked hard to rectify the major signalling faults.
"The signalling problems are now reported to have been caused by deliberate damage to signalling system cable.
"We are extremely angry and frustrated that mindless and irresponsible vandalism meant that many of our passengers had a terrible journey last night.
"Our staff did their very best to help people get home through the night, including organising and paying for alternative transport, however there is no question the plans of many of our passengers were hugely disrupted.
"In addition, our station and on-train teams worked hard to keep passengers updated, but we fully understand the frustration of passengers whose trains were unable to move for a lengthy period.
"Our operations team have worked through the night to get as many trains as possible back into position to allow us to run as good a service as possible this morning. We are, however, running some shorter trains than normal and some services have had to be cancelled.
"As a matter of course, we will work with Network Rail to review the response to last night's disruption. We are committed to learning any lessons and taking any steps required to improve the flow of information to passengers."
It was the second time this week that signal problems caused massive disruption to SWT services.
Robin Gisby, Network Rail's managing director of network operations, said: "There was an attempted cable theft at a substation at Farnborough last night which resulted in a complete loss of the signalling in the Farnborough and Woking area.
"This resulted in a very difficult journey and a lot of frustration for thousands of passengers who travel on the line into and out of Waterloo, with a significant number of trains delayed or cancelled.
"Cable theft and other forms of vandalism are serious crimes with significant consequences. These criminals continue to deny passengers the service they rightly expect and, through the massive cost to the industry, deny everyone improvements to rail services.
"We are doing everything we can to protect the railway and will continue to work closely with British Transport Police and other rail partners to do everything in our power to deter thieves and bring those who attack our network to justice."
Network Rail said anyone with information about cable theft should contact British Transport Police or Crimestoppers where they can report the crime anonymously and could receive up to a £1,000 reward.
:: An investigation has been launched after passengers on a packed rush-hour train forced open doors after it stopped for hours, partly in a tunnel, and jumped onto the track, only for the train to start moving again, it was revealed earlier this week.
The incident happened between London St Pancras and Kentish Town stations when a First Capital Connect (FCC) service, with hundreds of commuters on board, stopped because of power problems.
The Brighton to Bedford service train, which had a capacity of 476, was fully loaded, with many passengers standing when it stopped at 6pm on May 26.
The Rail Accident Investigation Branch (RAIB) said that by the time another train was sent to help the failed train more than two hours later, some passengers had used the emergency release handles to open the train doors to improve ventilation because the air conditioning was not working.
British Transport Police appealed for information about what it said was an attempted cable theft in the Farnborough area yesterday.
Investigators said the incident resulted in more than 9,000 minutes of delays and compounded existing problems on the network.
Superintendent Andrew Ball said: "At present it's unclear exactly how much damage was caused, but what we do know is that this incident compounded delays elsewhere and resulted in disruption to a large number of services.
"We've launched an investigation to determine the full circumstances and are appealing for anyone with information about the incident to contact us.
"Theft of metal and copper cable impacts on many industries and communities but those who steal, and in this case try to steal, simply do not care who their behaviour affects.
"As shown by this incident, the theft of railway cable can result in lengthy delays and cancellations to rail services, whilst elsewhere the theft of other items such as residential earthing cable or communications cable can have a serious impact on people's homes and businesses.
"The act of stealing, or attempting to steal, cable is extremely dangerous. What the thieves don't realise is that they are working on live cable, carrying high voltages, which can cause extensive burns. By attempting to steal it they are putting their lives at risk."
Mr Ball added: "BTP officers attended Woking rail station on Thursday following reports of overcrowding.
"Officers spoke to a group of passengers, who had left a train and walked back to Woking along the tracks, about the dangers of going on to the line without being directed to do so by rail staff or a police officer.
"We fully understand the concerns and frustrations of passengers, particularly the heavily pregnant woman, and we are sorry if anyone felt our officers were not sympathetic to their plight. Our clear priority is the safety of passengers and making sure they do not do anything that puts them or other persons at risk.
"Even when power may seem to be off, some parts of the tracks can remain electrified.
"Only recently, on Saturday 4 June, BTP officers helped a 22-year-old woman who received serious burns after forcing open the doors of a stationary train and walking on tracks in south Croydon before coming into contact with the live rail."