An Auckland dairy owner is in a critical condition in hospital after what police described a "violent and vicious attack".
Witnesses told Checkpoint they saw members of the public tackle the alleged offender and hold him down until police arrived.
A 24-year-old is in custody.
Police commended the bravery of members of the public who stepped in to help and believed their actions had saved the victim's life.
Listen
The dairy is in a block of a few shops, servicing a big community that knows the owners of the dairy well.
Locals were shocked about what happened near the intersection of Maioro St and New Windsor Road.
The Singaraju family live next door; Sumedha Singaraju said they saw the aftermath.
"We saw a guy get taken out on a stretcher, into [an] ambulance and we're like, 'oh, that must be dairy owner or something like that' ... after a little bit, we saw some guy covered in blood, trying to make a run for it, but the police got on him pretty quick."
The family visited the dairy regularly.
Srini Singaraju said it was very sad. "We're pretty worried for them... feeling very heavy, actually this is not an easy feeling."
Emergency services were called to the scene just after 10:30am Thursday.
It said a man had been injured with stab wounds and a woman, understood to be his wife, was also injured.
The alleged attacker was still at the scene, covered in blood.
Checkpoint spoke to the owner of Chandigarh Hair Salon next door to the dairy who said at the time customers intervened and managed to apprehend the offender until police arrived.
Cain Tai lives across the road from the dairy and was there grabbing a pie and a drink, right before the attack happened.
"That's one thing that I really can't get my mind around because that could have been someone that we could have saved, I'm really sorry to say that we weren't there."
Like all the locals RNZ spoke to, Tai was in shock and struggling to process what had happened to the friendly owners of their local shop.
"We've been here for almost a year now ... he's a good guy and he looks after his family, does what he has to do to make sure that his shop stays open.
"Just hoping and praying that he'll come back and he'll be okay so that we could go back and grab some more pies or something."
Local man Gary could not believe something like this happened in his neighbourhood.
"Now it's happening on the doorstep I think it's time to move out, it's getting too close to home."
That was a sentiment shared by many residents, Srini Singaraju said it was worrying that the attack took place in broad daylight.
Tai said violence was on the rise in the area. "You have to be aware always and stick around for your family, because that might be the last time you see them."
Police declined to comment as the early stages of the investigation were under way.