Police are trying to break up an all-night rave near the quiet Dorset village of East Lulworth.
Residents say they were disturbed throughout the night by loud music and large amounts of traffic.
Dorset Police were initially called just after midnight on Easter Sunday, and said they were working with other agencies to disperse party goers.
And they warned would-be revellers not to cross military firing ranges in a bid to reach the site, which has been set up illegally.
Local people called on officers to bring the situation under control quickly, and unplug the sound system, rather than 'monitor the situation.'
"Even in our front garden by Lytchett Bay you can just hear the low booming of bass so presume will go on all day too." said one commentator. "No fun for the residents there."
Alex Newell wrote on Twitter; "Can you not just cut the power supply to stop the god awful music?!"
While Jonathon Plant wrote: "There was no party! and all rules where followed! No one told them it was a party! time to move on."
Shortly after midday, police released a new statement, setting out what they were doing to alleviate the situation.
Deputy Chief Constable Sam de Reya said: “We are fully aware of the distress and disruption that is being caused to residents and visitors, many of whom have experienced consistent loud noise coming from the site.
"On a busy holiday weekend such an unauthorised event is negatively impacting on local Easter events, businesses and the rural community causing disruption as well as distress to livestock on farmland.“We are working closely together with partner agencies to assess all options to bring the incident to a safe conclusion and try to manage the considerable risks associated with a large-scale unauthorised gathering.
"It will come as no surprise that emergency services are already busy on a beautiful sunny Easter weekend and such irresponsible behaviour is adding to the demand.“As there are army training sites in the area, those attending the event are potentially putting themselves in danger by crossing these locations.
"There is also an amber wildfire risk and Dorset & Wiltshire Fire and Rescue are providing robust advice to not have open campfires or use BBQs in the open countryside.“Police officers have entered the site and given a direction for people to leave the scene of the unlawful gathering using powers under the Public Order Act.
"Due to the large scale of the event and impacts of dispersing such high numbers this process can take some time.“We will be investigating any criminal offences and ensure those found to be responsible are prosecuted.
"This is supported by vehicle checks in the area and on the site, deployments of officers with bodycams, the use of drones and the NPAS helicopter as well as other intelligence gathering methods.