Thousands of people were temporarily marooned in Brighton after Britney Spears' headline concert at the city's annual Pride event, after the police ordered the train station to be closed and services were suspended.
Passengers said the area around the train station descended into "mayhem", with photos on social media bearing testament to the chaos as vast crowds amassed and people complained of being crushed.
Police said they decided to close the station so they could impose crowd control measures, but the measures left many of the 57,000 people who attended the pop superstar's first live UK show stranded - with many reportedly resorting to sleeping on the beach.
“It was mayhem. How were we supposed to go back home?!” said Konrad Czapla, who was travelling back to the capital.
“A crush against a metal gate wasn’t exactly how I expected an otherwise wonderful pride to end,” said Robert Hart, a freelance journalist. “Seriously will people have to die before [Southern Rail] have their franchise taken or finally learn to run an actual service?!”
Southern Rail said crowd control measures were put in place by the British Transport police who said it was working with Sussex police “to assist with overcrowding issues”.
Revellers complained that staff had screamed at them as they were pushed into each other outside Brighton station as police guarded the doors, only to get inside to find an empty station and trains with plenty of space as services to London resumed at 2.15am.
Prior to this, people said trains were seen departing Brighton under capacity.
One passenger said she waited for at least three hours before getting on a train, and there were also reports of people fainting in the large crowds with others claiming emergency services did not provide travellers with water.
“Thousands of people had Brighton Pride ruined for them again this year because of the incompetence ofSouthern Rail andThameslink Rail,” said Mick Tayk. “How dare they display Pride colours on their trains and Twitter account when all they do is bring misery to the event.”
More than 300,000 people attended the event yesterday, one of the largest LGBT parties in the world.
She serenaded the crowd with classic hits including Baby One More Time, Oops!... I Did It Again and Toxic for 90 minutes before bringing the day’s festivities to a close.
The police and the train operators had expected hundreds of thousands of people to attend but it appears they were unprepared for the sheer volume of people with suggestions that there were not enough trains scheduled.
Nick Graham, who was was also caught up in the chaos, said: “Amazing day at Pride yesterday soured by the poor organisation and mass crush at Brighton station. I’m amazed nobody was killed or seriously injured. Seriously scary, and then trains were leaving not full!”
A Govia Thameslink spokesperson told the BBC: "At around 11.40pm the police requested that we close the station and suspend train services temporarily to help them control the crowd outside the station, and then allow people into the station in a controlled manner.
"We ran further extra trains, and the station steadily cleared, with the last extra train leaving at 2.15am."
A Southern spokesperson suggested that the chaos stemmed from a failure of the marshalling from the event to the station, for which the rail operator is not responsible for.
Sussex police said it had made 30 arrests throughout the day and that the crowds were controlled to ensure the safety of everyone.
Brighton & Hove City Council said there was overcrowding in some areas and an increase in calls to emergency services.
It opened the Brighton Centre conference venue for those needing a place to stay overnight while many others were said to have headed to the beach instead.
