United Airlines barred two teenage girls from boarding a flight in Denver because they were wearing leggings.

The girls, who were boarding an airplane at the Denver International Airport bound for Minneapolis, were turned away at the gate, the New York Times reported. The ordeal sparked sharp criticism on social media, leading United to defend the decision in a series of tweets Sunday.

The incident was first reported by Shannon Watts, founder of the gun control group Moms Demand Action and a passenger in Denver waiting to board a flight to Mexico. Watts told the Times in a phone interview that she noticed a “frantic” family with two young girls at the gate next to hers. She said the family was caught in a heated exchange with the gate agent, who told the teens, “I don’t make the rules, I just enforce them.”

In addition to the teens, there was one child also wearing leggings who was able to put a dress on so she could board the flight.

“The girl pulled a dress on,” Watts said. “But please keep in mind that the dad had on shorts that did not hit his knee — they stopped maybe two or three inches above his knee — and there was no issue with that.”

Watts said the girls were  “young teens” and  the child in a dress was either 10 or 11.

Jonathan Guerin, a spokesman for United, confirmed the teens were not permitted to board the flight because, as it turns out, they were the children of an airline employee and their attire violated the company’s dress code policy for “pass travelers,” a benefit allowing United staffers and their dependents to travel free on a standby basis.

Guerin said “pass travelers” are “representing” United and therefore, are not allowed to wear Lycra or spandex leggings, ripped or tattered jeans, midriff shirts, flip-flops, or any clothing that makes their underwear visible.

“It’s not that we want our standby travelers to come in wearing a suit and tie or that sort of thing,” he said. “We want people to be comfortable when they travel as long as it’s neat and in good taste for that environment.”

He confirmed that the two girls stayed in Denver to make an “adjustment” and waited to board the next flight to Minneapolis.

Following a day of criticism from celebrities, other United travelers, and internet observers, United issued a formal statement on the company website in which the airline wrote, “To our customers ... your leggings are welcome!”

“The passengers this morning were United pass riders and not in compliance with our dress code for company benefit travel,” the statement read. “We regularly remind our employees that when they place a family member or friend on a flight for free as a standby passenger, they need to follow our dress code.”

Watts, however, was not satisfied.

“I’m pretty sure yoga pants are a thing,” she told the Times. “They’re part of modern America. They’re a staple, a go-to clothing item.”

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