A 34-year-old local man witnessed the beginning of the attack in New Lynn Countdown which he said occurred about 2.40pm.
The witness said he had been in the store for about 10 minutes and was in the dairy section in one corner of the supermarket.
"It literally happened in front of me. I was just buying stuff and walking toward the milk aisle, and then suddenly I heard a person shouting loudly 'Allah hu Akbar' and just running.
So there was this lady in front of me and he jumped on her so she fell, so that person [the attacker] also sort of lost his balance. He also fell. Then he got up. But I was behind so I couldn't see his face but this person was wearing like a khaki jacket and he had a knife, a pretty big knife - like I would say the size of his arm. It was very scary. It was like a mini sword, not like a full sword. It was like a sword literally.
The 34-year-old witness said he wasn't sure if the woman who was jumped on got stabbed.
"She could have been. She was lying on the floor. I have a feeling she may have got stabbed," he said.
The witness said he didn't see the attacker's face as he was behind him.
"It was four or five steps away from me, and I had a clear path to run so I ran," he said.
"He [attacker] wasn't tall, I think he was about 5'8 or something. Slightly hefty guy. Then that lady fell and he went to the other side shouting 'Allah hu Akbar' and then I ran out. I was one of the first people, because I was right there. So I started telling people there was someone with a knife, 'come out, come out'. They didn't believe at the beginning because it was right in the corner of the store. Near the dairy section.
"One of the Countdown ladies started running outside, and then [others realised] this is real.
"At the beginning I thought it was a prank. Someone wanted to scare people and create some problem. Later I realised it was real so [I] started running outside shouting at people to come out."
"People by then had started coming out, people were scared, a few people fell down.
"The worst part was when I was entering I was looking at people who were standing in the [supermarket] queue. Most of them were aged people when I was entering. There were at least seven or eight elderly people I would say, 55, 60 years old."
"Suddenly there were like four people who looked like undercover cops, I don't know. They were there, they knew something was happening, immediately, within a few minutes, and then they went inside.
"While people were coming out I could see one lady wearing a white T-shirt completely bleeding and really panicking. People were trying to help her.
"We didn't know if this person carrying a knife had a gun, or a bomb, we didn't know. It was very scary so people started running out and all the cops started coming in.
"I saw another person bleeding from the shoulder really bad."