Two NSW Police officers were injured at the weekend's iconic Deni Ute Muster by an exploding butane gas bottle, while others were pelted with projectiles including eggs and bottles.
Thousands of revellers flocked to the annual country music festival at Deniliquin in the Riverina and police said the behaviour of the crowd was generally good until things became rowdy on Saturday night.
Local firefighters responded after several fires were lit outside drums and police were pelted with eggs, bottles, sauce and other objects.
Two officers suffered minor injuries when they were hit by shrapnel after the gas bottle was lobbed into a fire and blew up, while one of their colleagues had dirty diesel fuel thrown over them.
Police said most of the injuries were of a "relatively-minor nature".
Deniliquin Local Area Commander Superintendent Paul Condon said police were prepared for a busy festival because the warm weather.
"Unfortunately, the small few seem intent on spoiling the event for the greater majority, because any level of assault on our police is simply unacceptable," he said in a statement on Facebook on Sunday night.
"The police are there to keep people safe ... to have them attacked for striving to achieve this goal is simply disappointing."
There were almost 40 drug detections, compared to only eight last year.
Two dozen people are facing charges and most will appear in court over drug-related matters.
A 20-year-old man was charged with intentionally throwing an object at a vehicle and wilfully obstruct an officer in relation to the trouble on Saturday night.
He's due to face Deniliquin Local Court on November 7.
Police will now work with the festival committee to ensure there isn't a repeat of the incidents next year.