Brighton and Hove police commander Nick May has warned people to stay away from a rave.
Chief Superintendent May spoke out as officers close several roads in the Steyning area.
Sussex Police said: “We are aware of and responding to a large unlicensed music event in the Steyning area this morning (Sunday 27 June).
“Multiple road closures are in place and people are asked to avoid the area if possible.
“Anyone planning on attending the event is warned not to travel to the site – officers will be taking action against those found doing so.”
Chief Superintendent Nick May said: “Our priority is ensuring the safety of the community and everyone in the vicinity.
“We have a significant number of officers at the scene working to bring the event to a safe and timely conclusion.
“This is an ongoing matter and we thank the public for their patience and co-operation at this time.”
