A package with coolers containing 18 human heads was found at Chicago's O'Hare airport on Monday. According to the New York Daily News, airport employees found a grisly surprise when they opened the mysterious package.

Some of the heads were still covered in skin. It was determined that they were medical specimens from Italy which had gotten misplaced. Tony Brucci, chief of investigations for the Cook County medical examiner's office told the Chicago Tribune that the specimens were shipped on Lufthansa airlines before Christmas, but their final destination was not clear in the paperwork that accompanied them.

Customs officials forwarded the coolers to the medical examiner's office after X-rays revealed that they contained 18 human heads.

Brucci told the Tribune that his first thought upon being notified that a box of heads had been found at the airport was, "Oh, boy. Here we go."

U.S. Customs, Homeland Security and the FBI are all investigating. So far, the intended recipient of the gruesome cargo has yet to come forward.

"That's the big thing," said Brucci. "Where were they going?"

Authorities said foul play is not suspected.

Watch video about this story, embedded via Chicago's WGN Channel 9, below:

[image via Flickr, creative commons licensed]