(CBS) — The CTA is investigating an incident from Wednesday evening in which someone was videotaped riding on the outside of a Red Line car in the downtown subway.

The video was posted on the Facebook page, “People of the CTA.”

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And the video shows a person on the outside of a CTA Red Line car.

“He held on for his dear life. I don’t know what made him do it,” says 23-year-old Saad Ibrahim, a senior at DePaul, who shot the video.

Ibrahim says the video shows one person clinging to the outside of his train as it left Lake Street. But there were actually two people on the outside between Lake and Monroe, he says.

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“I was first in shock.  I was like, what the hell is going on?  But then once I realized the guy wasn’t flying off or anything, I had Snapchat open on my phone and I took a Snapchat video,” he tells WBBM’s Steve Miller.

Ibrahim says he thinks what they did was stupid. Another side of him thinks it was awesome, though.

The CTA does not think it was awesome.

“We are aware of the incident, are working to identify the individual, and will pursue appropriate charges. Any reports of this kind of reckless activity are taken seriously and are fully investigated,” the agency said in a statement.

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“Actions like this are extremely foolhardy and display an astonishing lack of common sense and judgment. This is not only illegal, but dangerous not just to the person involved but other passengers as well. Incidents like this can have tragic consequences for not only the individual, but for other CTA customers and employees.”