“[Those hurt] were really badly injured ... we were in shock.”
The incident involved two groups - a man and woman in one and four people in the other - but she didn’t know what it was about.
One person was been taken to hospital with critical injuries and the other with moderate injuries, police said.
Two ambulances were sent to help the injured pair, a Hato Hone St John Ambulance spokeswoman said.
Both were taken to Middlemore Hospital.
No one from Z could immediately be contacted.
Police said anyone with information should contact them online at https://webforms.police.govt.nz/en/update-report or call 105, referencing job number P060475788.
Cherie Howie is an Auckland-based reporter who joined the Herald in 2011. She has been a journalist for more than 20 years and specialises in general news and features.