The person continued through into the terminal, setting in motion a security emergency.
Images of long queues emerged on social media and Auckland Airport said it would restart screening, but said it would take some time to clear the backlog.
Several members of the public tweeted about the security shut-down, with one saying that "Kiwi travellers are very relaxed in the face of massive delays".
At least four flights have been affected.
Air New Zealand and Virgin Australia flights to Christchurch and Gisborne at 7pm have been delayed as well as flights to the Bay of Islands with the same two carriers.