"He escorted me out of the building. He opened the door, and so I had to leave," said Lapriss Gilbert.
Gilbert says the security guard told her she had to leave or she would go to jail.
Gilbert says the T-shirt was a gift from her mother, who is a gay rights activist. The guard showed them a federal code with nothing that seemed relevant.
"Just show me where that statement says lesbian, gay, homosexual - anything close to it ... and we'll be happy to leave," said Tanya Gilbert, Lapriss's mother.
Onlookers began voicing their opinions as well.
"Stating their opinions ... People were getting on the phone calling the police ... and, it just turned into a mad house," said Derek Hughes, witness.
As the situation escalated, another man was threatened with arrest.
"He was going to lock him up too because he was like, 'Well, are you with them?' And he was just like, 'Yeah!' And I'm like, 'Oh wow, you're going to go to jail with us,'" said Lapriss Gilbert. "Everybody's going to go to jail over a T-shirt!"
A supervisor finally overruled the guard. The guard works for Paragon Systems and was hired by the Department of Homeland Security. The guard had no comment. However, his superiors issued statements.
A federal spokesperson says it was "inappropriate action, inconsistent with our policies."
According to Paragon, "Action will be taken against the guard. We do not condone this type of behavior."
Gilbert's mother, who has a PhD in clinical psychology, suggests sensitivity training for the guard. She also said that she could do it herself.
Gilbert and her mother plan to sue, alleging a violation of civil rights.