Four police officers and a police dog have been injured while attempting to shut down an illegal rave in Twyford Woods, off the A1 towards Corby Glen.
One officer was seriously injured in the attack. The injuries are described as not life-threatening.
Officers were called to the scene at around 11pm last night (Saturday) after a member of the public complained about loud noise and anti-social behaviour.
Police spokesman Tony Diggins said: “Police attended and we actually came under attack by members of the crowd who were gathering to set up an illegal rave.
“As a consequence, four police officers were injured, two of them serious but not life-threatening, and a police dog was also injured.”
Three women from the Norfolk area were arrested at the scene.
Officers immediately began clearing the site of sound equipment and power generators. Mr Diggins said: “As a result, the majority of the people who were attending it have left.”
However, motorists are advised to steer clear of the roads surrounding the woods this morning while officers’ enquiries are completed.