An alligator was found crawling around at Chicago's international airport O'Hare on Friday.
The foot-long reptile was discovered under an escalator in Terminal 3 by a passenger.
Speaking to CBS 2, Tineka Walker, who works for the airport, said: "I was out there, and a passenger had pointed out that there was an alligator up under here.
"I looked, I said, 'What?'"
The animal was captured when police officers arrived and put a rubbish bin over it.
Chicago Police spokesman Jose Estrada told AP: ""We don't know where it came from or how long it'd been residing in the airport facilities."
Chicago Herpetological Society is taking care of the alligator but said it was "in pretty bad shape" after being underfed by its owner.
A Chicago Herpetological Society official told CBS 2: "What if a little kid grabbed this, thinking it was a toy? That could do a nasty job."
A photo of someone holding a small alligator on a Blue Line train was posted on Twitter on Friday and it is believed that they realised they could not take the animal through security and just released it in the terminal.