The 38-caliber handgun was reportedly found alongside Santana's ID.
The TSA says once the gun was discovered, Santana, whose real name is LaRon James, took off running.
Santana is a New York native who is originally from Harlem but now lives in Englewood, New Jersey.
A Transportation Security Administration spokeswoman says agents noticed the firearm in the bag passing through an X-ray at a security checkpoint. That's when authorities say the suspect took off.
(The Associated Press contributed to this report.)
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