Thousands of people were unable to get home from Pride after overcrowding caused chaos at Brighton station.
Southern Rail said it had put crowd control measures in place after 'overcrowding concerns'.
Twitter account Sussex Incidents said: "Sussex Police are holding an emergency planning meeting at 1am. We are waiting further news."
Portslade councillor Penny Gilbey said on Twitter: "Council agreed with the police to open up the Brighton Centre as a safe space rest centre. This will provide safe rest space & water but not beds because the crowds currently seeking to leave Brighton by train far outnumber the remaining additional train capacity through to 2am.
"Trains to London, after 2.00 am, resume at 4.30 am. Fortunately we have fine weather and it may be that crowds will disperse and/or wait throughout the city centre for the rest of the early hours and through to morning. However, council reviewing other options if required."
Related stories: 'Dangerous' crowds at Brighton station after Pride
The crowd surge took place from around 11pm, after Britney's Brighton Pride set finished at around 10.30pm.
Passenger Sarah Garvey, who was travelling to London, said the station temporarily closed, but when gates opened 'everyone pushed through'. She described the situation as 'dangerous'.
Southern Rail said on its Twitter page: "#Brighton station may be closed at short notice due to overcrowding. Speak to station staff for further information #SNUpdates"
Sussex Police said: "Brighton Railway Station is very busy. If you are waiting for a train, please be patient and listen to the announcements being made. @BTP , supported by us, are controlling the crowd to ensure the safety of everyone. Please stay with your friends, keep calm and keep hydrated."
Brighton and Hove Buses said: "Due to an incident at Brighton Station, all services are currently unable to serve Brighton Station, Queens Road or Terminus Road, all services are therefore currently on diversions or terminating short. Apologies."
Just before 1pm, British Transport Police Sussex tweeted: "#Brighton station is currently extremely busy - we’re working to get you home safely. Please stay calm and listen for announcements."
Were you caught up in the chaos? Let us know by emailing copydesk.sussex.co.uk