SIX people suffered burns to the legs following an explosion from a firecracker at the Bombs Away show at the Grafton District Services Club on Saturday night.
Police are reviewing CCTV footage of the event and club manager Arthur Lysaught said staff had a "fair idea" who the culprit was, but independent witnesses would help the case.
"It was the only real negative on the night," Mr Lysaught said.
"It's fools that act in this manner that put the continued provision of entertainment for the younger members of the Grafton community at risk; and what about the innocent bystanders who were injured?
"Lets hope the police give the person responsible what they deserve. I can guarantee our club will."
Mr Lysaught said the injured partygoers were given first aid for minor burns at the club and none needed further treatment.
He said the diameter of the cracker was about five centimetres and it was placed under the stage where the DJs were playing.
Though the act continued playing, the incident marred the launch of the new G-Night Club which promises to boost the local music scene.
Mr Lysaught said 650 patrons attended and the tickets were sold out by Friday morning.
"The atmosphere was exceptional, production was first class with the latest technical gear including large screens either side of stage.
"Dress standards were very high and enforced."
Though four people were refused entry at the door and three others kicked out for intoxication, Mr Lysaught said the majority of patrons were very well behaved.
"Bombs Away had a ball and have requested a return date later in the year," he said.
Other big acts on the way include beat-boxer Joel Turner and Aussie dance juggernaught Sneaky Sound System, with more to be confirmed.