LaRosa said Shooters Saloon was hosting an EP release party and "everything was going good".
"The crowd has been here before, no problems.
"[It] must be a gang or something turned up. We saw them coming up the road with cricket bats and closed the doors and all hell just went loose.
"The people from in here ran out and it all sort of happened in the street away from us, but they did break a few vehicle windows, they did do some damage.
"There was some gunshots fired but that was away from us, about 100 metres away from us.
"I got hit on the head with a cricket bat and it required a few stitches. I think that's the only injury, no one got shot or anything."
The fight lasted a couple of minutes before one group fled on foot down nearby Mostyn St, police said.
A firearm was then discharged on Mostyn St and Aitken Tce.
Police are trying to locate those involved, and no arrests have been made at this stage.
LaRosa said "it was pretty scary" when staff heard gunshots.
"This is a freak thing. It hasn't happened in the 12 years I've been here - we've never had this sort of thing."
He said after the altercation patrons left and the bar was closed. He said police are reviewing CCTV footage.
Police are appealing to the public for further information.
Anyone who has information is asked to call police on 105, quoting the file number 220206/3111. Information can also be provided anonymously by calling Crime Stoppers on 0800 555 111.
