Revellers were left stranded for several hours as huge crowds tried to make their way home from Brighton Pride on Saturday night.
Passengers reported “chaotic” scenes outside Brighton train station, with pictures on social media showing hundreds of people waiting to get onto the platforms.
Southern Rail said measures were put in place following concerns of overcrowding, having earlier warned that the station could be closed at short notice.
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.
Another traveller, Geraldine Carr, said she arrived at the station at 11.50pm hoping to catch a train back to London, and described the situation as a “shambles”, finally getting home at 5am.
The 38-year-old said: “The queue was insane. When the barriers opened people were slowly being let in, but this of course led to people being pushed and shoved.
“I saw one woman have a panic attack and could not see any paramedics around to help. If a serious incident happened while we were waiting it would have been very serious.
“Eventually after an hour or so we got through the gates and were shoved into a train. This was chaotic as people were running.”
There were also reports of huge queues at Three Bridges station in Crawley, where passengers had to change for trains back to London.
Brighton and Hove City Council opened up the Brighton Centre conference venue for those needing a place to stay overnight – but quashed rumours that 4,000 people had turned up.
A spokesman said: “As part of our emergency planning role, the council was prepared to make the Brighton Centre available for the Pride event.
“The venue has been open for a few hours overnight and will be used by the coastguard and SECAamb as well as to provide support to people our partners have asked us to help.
“Reports that 4,000 Pride goers are currently at the Brighton Centre are untrue. While the Brighton Centre has capacity for many thousands of people, we have only received six people at the venue. We are not expecting the numbers to rise significantly from this point but we are ready to help further if needed.”
Many people were said to have given up trying to travel, and headed to the beach instead.
Britney Spears was the headline act at the country’s biggest Pride festival, with organisers anticipating up to 100,000 fans would flood in to Preston Park to watch her show.