Police broke up a rave and seized sound equipment at a west Norfolk country park.
Officers were called to Bawsey Country Park, on the B1145 between King's Lynn and Gayton, in the early hours of Sunday, July 3.
A spokesman for the Norfolk force said a member of the public had reported suspicious activity at the former quarry workings.
They added: "Shortly after 3am officers discovered approximately 50 people in Bawsey Country Park with music being played loudly.
"Police vehicles were used to close entrances to the site to prevent more vehicles from entering, and officers monitored the event throughout the early hours of the morning before equipment was seized and attendees asked to leave."
The force said enquiries into the event were "ongoing".
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