The two parties immediately clashed and a serious brawl erupted, resulting in a number of people becoming seriously injured.
Officers say there’s no clear motive for the clash and detectives are still unable to determine “why the other party has attended, or the relationship between the two parties”.
“For something like this to happen, with six victims overall, for people that were just meant to be having a nice barbecue after work, it’s obviously of great concern for us,” Detective Senior Constable Erin Hardie said.
“For two people to be injured in such a way, that’s obviously of great concern for us to find out who has been involved in that.
“At this stage we have no idea in relation to motive, or why the other party has attended, or the relationship between the two parties.
“Our inquiries are still ongoing… but some of the calls have come through to say that there was between 40 to 50 people.
“They sustained head injuries… significant head injuries.”
Hardie said “planks of wood” and other items that may have been used as weapons were found in the vicinity following the brawl.
She said a number of those hurt during the incident self-presented to “various hospitals” around the city.
A 36-year-old Williams Landing man, a 28-year-old Tarneit and a 35-year-old Tarneit man currently remain hospital with serious injuries.
“Today it’s just a case of processing the crime scene and trying to work out exactly what’s happened,” she said.
“We’ve got CCTV at a number of businesses which we’ll be sifting through.
“If anyone has seen anything, if anyone knows anything… contact police or Crime Stoppers.”