Police were bitten and assaulted at the Listen Out festival in Perth when about 300 people tried to gatecrash the event.
Officers were called to HBF Arena in Joondalup on Sunday afternoon when people began throwing rocks at patrons and pushing external fencing to gain entry.
There were similar incidents in 2015 and 2014 (caught below on video) at the same festival.
The group threw objects at police, which included the canine and mounted squads, with one officer bitten and two others physically assaulted.Four people in their 20's have been charged with offences including assaulting a public officer, obstructing police and disorderly behaviour.
Police also issued 15 move on notices and received a complaint that windows had been damaged at the venue.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
CCTV footage has been viewed and investigations are continuing.
