Countdown is warning people to avoid taking out any feelings of fear and uncertainty on its staff as New Zealand enters another day under level 2 restrictions, with Auckland at level 3.
"We had quite a serious incident in one of our stores in Auckland last night," spokesperson Kiri Hannifin told Newstalk ZB.
"All of it is unnecessary and all of it causes a great amount of stress and harm to our team, who are simply doing their best and would probably rather be home with everybody else.
"The vast majority are very kind but those who are not, it creates a very impactful experience for our team."
Hannifin described the incident as "really disheartening and horrific".
Meanwhile, a surge in online orders is causing delays to Auckland deliveries.
Some customers have received an alert saying orders could arrive as late as 10pm tonight – hours after the scheduled time.
Hannifin said stores are "definitely feeling the pressure of busyness".
Extra online packers and even staff from support centres have been roped in to cope with demand.
Foodstuffs North Island CEO Chris Quin told Newstalk ZB he saw encouraging levels of mask use and QR code scanning in Auckland today, but not so much in other parts of the country.
"We are working hard across all stores to encourage that QR scanning is easy to do, reminding people positively that it really does help when they do that."
But the mad panic appears to have slowed today.
"People have been calm and they've been keeping it together and we have been able to make sure people can get what they need," said Quin.
Earlier today, Prime Minister Jacinda Ardern said there was something about human behaviour which led to people panic-buying toilet paper and flour.
"It's just so clear that, after repeated attempts, there is something about human behaviour that says when restrictions are in place people will immediately feel the need to buy toilet paper, and I cannot explain it," she said.
Ardern reminded Kiwis supermarkets will remain open under alert level 3 and 2.
