Residents reported hearing gunshots before police suddenly swarmed the waterfront park.
The witness said they did not know who the man and woman were.
A cordon was in place around the public toilets and playground located on the popular park.
Acting Detective Senior Sergeant Shane Pilmer, Whangārei CIB, said police did not believe there was an ongoing risk to the wider community.
“We understand this incident would have been unsettling for the wider community and we appreciate the assistance from the public during this time.”
Police were calling for witnesses or anyone with information to come forward.
“The key focus for us is determining the series of events that led up to this tragic incident,” Pilmer said.
Police investigate the homicide scene on Beach Rd in Onerahi, which is heavily guarded. Photo / Denise PiperNeighbours said they are shocked and saddened by the incident.
Rahera Tau and her family live close to the park and use it often, either for exercise or for her two kids to play on the playground.
She said she was sad to hear there was a shooting and felt a bit unsafe.
“It’s so sad, especially in a kids’ area, by a playground. People won’t want to come out here anymore.”
Tau said the area is used often by freedom campers but is also popular for fishers and dog walkers.
Police officers, some armed, help with the cordons in Onerahi, stopping people to ask if they had heard or seen anything. Photo / Denise PiperAt the time of the incident, the reserve was busy with fishers and freedom campers, who left after being interviewed by police.
People reported seeing more than eight police cars in the area, as well as armed police and multiple ambulances.
Hato Hone St John sent three ambulances, an operations manager and one rapid response vehicle to the scene.
Pilmer said cordons around Beach Rd would remain in place.
He asked the public to avoid the area as police carry out a scene examination and further enquiries.
Anyone with information can contact police on 105 or online via https://www.police.govt.nz/use-105, quoting job number P061751387.
Information can be provided anonymously through Crime Stoppers on 0800 555 111.