More than 1,000 people have attended an illegal rave in Berkshire.
People living near the site, next to the Sandhurst Bypass, near Crowthorne, began calling police at about 0200 BST.
Thames Valley Police said they wanted to reassure the public they had been monitoring the site.
Several hundred people remained at the rave on Sunday afternoon. The organisers said they were peaceful and would clear away any mess.
Some revellers had travelled from South Wales and Bedfordshire.
A police spokesman said the number of revellers increased dramatically within an hour of the rave beginning.