Around 200 people have taken part in an illegal rave in Burgess Hill.
Police were called to Burgess Hill on Saturday to deal with a rave and to turn people away.
200 people were inside a building in Victoria Road, and around 300 more began arriving for the event using the trains.
People began turning up in the town at around 11.30pm on Saturday (16 December).
Local officers worked with the British Transport Police in a bid to identify people travelling to the illegal event.
Victoria Road was closed off; police began turning people away, while remaining at the site.
Sussex officers say the police presence remained to ensure those who were trying to attend the event safely left the area.
Detective Sergeant Dave Morton said:
“We did request that if anyone was on their way to the town or the rave, that they did not attend.
“The temperature was close to freezing last night and many people were turning up outside in the cold conditions.
“Although there are powers available to the police to close down illegal gatherings such as this, before exercising these powers an assessment has to be undertaken to determine whether or not such a gathering can be closed down safely and effectively.
“The assessment was that it would not be possible or safe to close the event in view of the time of night and the numbers of people arriving in the town to try and attend it.”
Sussex police report the event was brought to a conclusion at 5.30am on Sunday morning.
There were no arrests but police are continuing to make inquiries.
Anyone with any information about the rave, is asked to contact police online or ring 101 quoting Operation Corvette.