New Zealand Customs agents discovered an unclaimed backpack filled with methamphetamine, and it seems to have been a special delivery from San Francisco.

The bag was intercepted at Auckland International Airport on Saturday, June 14, having arrived on a flight from San Francisco. As New Zealand Customs explained in a Facebook post, the bag was "referred to Customs by border partners who noticed some inconsistencies in x-ray imaging."

Customs agents found a vacuum-sealed package inside the bag, and the contents then tested positive for meth.

It seems likely the bag can be traced to whichever passenger checked it, but the situation is apparently under investigation.

"Customs continues to work closely with our border agency colleagues to disrupt the organised criminal groups behind these drug importations," says Chief Customs Officer, Tracy Henderson, in a statement. "Border agencies work swiftly to investigate any suspicious activity through our airport. It’s the sharp instincts of skilled frontline officers that continue to stop illicit drugs from making it into our communities."

It's not clear what flight was associated with the bag — both Air New Zealand and United Airlines fly to Auckland out of SFO.

Last month, a Southern California woman was arrested at SFO for allegedly trying to smuggle 151 pounds of marijuana on a flight to Frankfurt, Germany in multiple roller bags.