The Fire Service said it had received reports of smoke coming from under a door on the first level of the terminal, but it was found to be a false alarm.
"We do have the international terminal building in evacuation," said an Auckland Airport spokesman earlier this evening.
Only one of about 20 zones in the airport were evacuated, but because the area was airside it meant passengers were being stopped from boarding and planes on the tarmac were grounded, the spokesman said.
One passenger, who does not want to be named, was one of about 80 people who followed staff outside to the airport tarmac.
He had just gone through customs and was waiting inside the international terminal when the fire alarm went off.
"No one knows what's going on, so for some that kind of made it a little bit more nerve-wracking.
"There was no information as what people were supposed to be doing."
Abby Stiefel was supposed to be hopping on a plane to San Francisco when the gates were evacuated.
She says hundreds of people had to leave the departure gates, but no one seemed to have any idea what was going on.
"People are still getting coffees and beers. There's not a panicked feeling at all."
- Additional reporting: Newstalk ZB
