One arrest has been made and vehicles, a generator and other equipment seized after police dispersed an all-night illegal rave attended by thousands of people near Bath.
Avon and Somerset Police said that the first reports of the unlicensed music event were made around 11.20pm on Saturday, but it was not shut down until the following afternoon.
After officers arrived at the former Charmy Down airfield, in Upper Swainswick, they established there were around 1,000 people there and called for back-up, the force said.
Dedicated patrols on duty to respond to unlicensed music events were redeployed to the incident and the approach roads closed.
But the force said people were abandoning their vehicles and walking to the site, and it was still turning people away after dawn on Sunday.
Avon and Somerset Police said the risks to public safety of closing an event attended by more than 3,000 people in dark and wet conditions were too great with resources already dealing with other “significant incidents” across the force area, including 120 999 calls.
The music was eventually turned off by 1pm on Sunday and the majority of the site closed by 4pm, police said.
But officers then had to deal with a group trying to continue the event in a neighbouring field, it added.
One person was arrested for failing to comply with a notice to quit the land and five vehicles, a generator and other equipment seized, police said.
An investigation is under way to identify and take appropriate action against those responsible for the event.
Chief Superintendent Ian Wylie said that the impact of the rave was felt by other emergency services, with around eight 999 calls to the ambulance service linked to the event.
He added: “We’re sorry for the disruption caused to so many residents. It’s frustrating that we are having to pull officers away from our 999 response to deal with the selfish actions of the organisers of this event and those attending it.
“They knew full well the disruption this would cause and the ongoing risk to public health of large gatherings due to Covid-19.
“We brought officers in from their rest days and called on support from neighbouring forces to close down this event.”
Witnesses or people with evidence should call the police on 101 quoting reference 1414 of 18 July.