About 2.5 hours ago, according to WCCO:

Two separate K-9s stopped near two vending machines in different areas of the terminal, airport spokesman Pat Hogan said.

About 200 passengers on a Sun Country flight were affected, Hogan said. Outgoing flights were delayed and incoming flights were diverted to the Lindbergh Terminal.

Humphrey is the smaller airport that handles Sun Country and many charter flights. I'm in Humphrey maybe once every other year, while I fly through Lindbergh roughly once every other month. Chances are this isn't holding up traffic too much.

Related point: One of the light-rail trains near the airport struck a car, injuring two people. (Noted from Hugh Hewitt's show.)

UPDATE: Ed notes the location of the vending machines.

UPDATE 2: The machines have been hauled outside with a forklift, and it turns out the alarm was false. Littlest Scholar asked if it was just bad candy. Turns out one machine's an ATM, ruining her theory.