(CBS) — Millions of visitors pass through O’Hare airport every year, but one visitor’s appearance caused quite the stir earlier this week.

An alligator seemed to appear from nowhere, crawling around Terminal 3, on Friday.

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“I was out there, and a passenger had pointed out that there was an alligator up under here,” Tineka Walker of Universal Security tells CBS 2’s Mai Martinez. “I looked, I said, ‘What?’”

Sure enough, there was.

Walker radioed airport police for help. She wasn’t the only one laughing at the bizarre situation.

“Figured somebody was messing with us,” Chicago Police Officer Anthony Oliver says.

Department of Aviation workers caught the alligator using a broom and dustpan, and Chicago police held it for the city’s animal control department.

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An official with the Chicago Herpetological Society says it’s very fortunate someone wasn’t hurt.

“What if a little kid grabbed this, thinking it was a toy? That could do a nasty job,” he said.

As for how the alligator got to O’Hare, that’s still under investigation. But it’s possible his owner brought him by train on the Blue Line, based on a picture that someone posted on Twitter Friday.

“They probably realized they couldn’t take it through check point, and just let him go, but oh my God,” Walker said.

It gave a lot of people a lot of laughs, but it’s illegal to keep an alligator as a pet in Illinois.

An alligator matching the one found at O'Hare was spotted on the Blue Line last night.  Photos appeared on Twitter. (Credit: Twitter)

An alligator matching the one found at O’Hare was spotted on the Blue Line last night. Photos appeared on Twitter. (Credit: Twitter)

The alligator will need to be treated for about six months because it appears the owner didn’t feed it properly and stunted its growth.

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After rehab, it will likely be given to a reptile park.