Some 2,000 people attended the gathering in fields near Steyning, West Sussex, on Saturday night and blared music from speakers overnight. It is thought many of these people had travelled long distances, despite coronavirus rules banning gatherings of more than 30 people.
Police detained suspects on suspicion of drink and drug-driving and possession of drugs and theft, Sussex Live reports.
Eight people were identified as potential organisers of the rave and arrested, while sound equipment was seized. One of those arrested is from Redditch, Worcestershire, more than 150 miles away.
Sussex Police said it was the “largest, unplanned operations” the force has experienced in recent years.
Roads were closed into Sunday morning as officers checked motorists were not above the drug and drink driving limit.
Two police cars were involved in crashes with vehicles which had been at the event. One officer was assaulted.
A spokesperson for Sussex Police said: “One officer was assaulted while attempting to detain an individual resisting arrest.
“A police community support officer is also being treated for a suspected broken arm following a collision involving a police car and a vehicle being driven by someone leaving the event.
“The driver and passengers of the second vehicle were also taken to hospital as a precaution.
“A 20-year-old man from Redditch, was arrested on suspicion of driving while under the influence of both drink and drugs in relation to this collision.”
People who organise large-scale gatherings that breach Covid guidelines can be fined up to £10,000.