Police say a fire that prompted an evacuation in the Porirua Kmart earlier today may have been arson.
A spokesperson said the fire started in the Christmas decoration aisle and it was believed to have been deliberate.
Police are checking CCTV footage of the store.
Fire and Emergency central shift manager Belinda Beets said the centre's alarm was activated just after 4pm.
"We had at 4.10pm a manual call-point activated followed by a sprinkler system and several triple one calls to indicate there was a fire in the mall - in Kmart.
"We have located a fire but that's been well-contained and controlled by the sprinkler system."
"Initially we had four pumps and an aerial appliance - that's the one with the big ladder on top. The ladder and the two appliances were stood down we've still got two in attendance there at this stage."
She said it was not known how the fire started, but there would be an investigation.
The North City Shopping Centre will remain closed tonight while the investigation and a clean-up is underway.
A director for the mall manager Colliers International, Gerard Earl, said systems worked as expected and the fire was extinguished.
He said K-Mart faces a big mop-up job from the sprinklers but the rest of the mall will re-open as normal at 9am tomorrow morning.