Police said the attack occurred when the man entered the Countdown supermarket in the city’s New Lynn suburb as people were doing afternoon shopping.
“Police have located the man and he has been shot. He has died at the scene,” they said, offering no information on the man’s motivation in carrying out the attack.
The St John Ambulance Service said six people were taken to hospital, three in critical condition.
Details of the attack were scarce, with some witnesses saying the man was wielding a knife and others describing hearing gunshots.
Auckland is currently in Covid-19 lockdown as it battles to contain an outbreak of the highly transmissible Delta variant.
Prime Minister Jacinda Ardern’s office said the New Zealand leader was being briefed on the situation and would hold a press conference later Friday.
There was a similar supermarket attack in Dunedin in May when a knife-wielding attacker wounded four people.
Police Commissioner Andrew Coster said authorities were confident the man was acting alone and there was no further danger to the community.
A video posted on social media showed shoppers in the New Lynn supermarket shortly after the attacker struck.
“There’s someone here with a knife … he’s got a knife,” a woman is heard saying. “Somebody got stabbed.”
A guard asked people to leave the shopping mall shortly before about six shots rang out.