Detective Sergeant Scott Hunter said the groups did not know each other.
"It's just wrong place at the wrong time," he said.
"We don't believe there will be any retribution or reprisals in regards to this.
"However, we obviously need to find out how this incident started or if there is a common catalyst."
He said hundreds of people could have seen the attack and encouraged witnesses to come forward.
A team of 15 police officers were last night working on the case. They had yet to interview either of the stabbed men.
The 22-year-old man with facial injuries, described as being of Asian appearance, was awaiting surgery in Middlemore Hospital to fix sliced nerves in his face and a fractured eye socket.
Renowned plastic surgeon Professor Swee Tan, based at Hutt Hospital, said the man's facial movements and sight could be affected long-term. "If the fracture is unstable we usually use titanium plates and screws to hold it together."
The four charged men are due to appear in the Auckland District Court tomorrow.
Anyone with information should call Auckland CIB on 09 302 6400 or Crimestoppers on 0800 555 111.