An Auckland man was left shocked today after discovering a toddler locked inside a vehicle at a supermarket in sweltering temperatures.

David Le Roux said he parked next to a heavily tinted, black SUV in the carpark of PaknSave Silverdale about 12.30pm.

While walking past he noticed a figure move slightly, before peering in and seeing a toddler inside.

"I saw movement and I looked in the back window which was quite heavily tinted and there was a baby sitting in a baby chair. It was a black car and all the windows and everything were closed and the temperature outside must have been about 28 degrees.

"I was quite shocked, you hear about these things on the radio, kids dying [left in cars] and here's one right next to me."

He tried the doors but all were locked. After getting the attention of another shopper - who stayed with the child - he went inside to get help from supermarket staff.

"I called the duty managers and they rushed outside. The little boy, he must have been about 2, luckily he wasn't strapped in. He was okay, he wasn't stressing yet.

"One of the managers was a lady and she talked to him and he was smiling at her and she asked that he open the door, and he couldn't because the child lock was on. So she coaxed him to the front door and he managed to open that and they took him inside."

He then left the child in the hands of supermarket staff.

"They were on to it right away, they took it very seriously."

After doing his shopping he returned about 10 minutes later and the car was still there, unattended.

A Foodstuffs spokeswoman confirmed the incident at the store this afternoon, but said the child was "absolutely fine" due to the quick action of everyone involved.

"We are aware of an incident at one of our stores where a child has been left briefly unattended in a hot car.

"A customer notified store staff who acted swiftly to remove the child from the vehicle and tracked down their caregiver – fortunately despite the intense temperatures the quick action of all meant the child was absolutely fine."

The spokesperson said it was a timely reminder, especially given the heatwave the country was currently experiencing, not to leave children or pets in vehicles.

"Customers should leave pets at home and take their children into the shop with them rather than leave them in the car.

"Even a quick trip in-store could lead to discomfort for someone left in a hot car, and it's simply not worth taking the risk."

Police told the Herald they were "not immediately aware of the incident, but urge anyone with more information to contact Police".

"In general, we encourage anyone who sees a child in distress to contact emergency services immediately."