The incident happened about 5:50 a.m. when Bob Young, of Ohio, stumbled upon the unattended weapon in a Concourse C restroom.
"Oh my God," Young said. "It was unnerving to see it sitting there."
Concourse C is beyond the main terminal, where all travelers go through security checkpoints.
Young immediately decided not to touch the weapon, which was in a holster and off to the side of a toilet. He was rushing to leave the restroom to alert airport security about the find when he nearly bumped into a security agent.
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