Firefighters are standing down after "black smoke" was seen pouring out the side of the new Westfield Newmarket mall.
Emergency services rushed to the scene, located on Broadway St, after getting a call at 7.40am.
Fire and Emergency New Zealand (FENZ) shift manager Craig Delly said the reports of smoke turned out to be coming from a diesel generator exhaust and there was no fire.
"We are there as a precaution," Delly told the Herald.
A staffer from Auckland Mini Garage, who did not want to be identified, told the Herald she called the fire brigade after seeing black smoke coming from the side vents of the building.
"There's still quite a lot of fire crews here at the moment but the smoke seems to have settled down," the staffer said.
Police confirmed they were at the scene, along with Fire and Emergency New Zealand.
They were called to the mall, located on 277 Broadway, at 7.45am.
It comes just one month after the $790 million development opened, along with 40 shops.
Reports of a fire at Newmarket also resulted in congestion at the Gillies Ave off-ramp on the motorway.
The NZ Transport Agency warned motorists in the area about 8.40am to expect some delays due to a temporary road closure at Mortimer Pass.
''Please take extra care until the road reopens''.
The road was reopened just before 9am, however, and queues in the area are starting to ease.