DENVER, Colo. -- Two girls were denied entry on a United Airlines flight on Sunday morning because they were wearing leggings.

Shannon Watts, who witnessed the events at a gate at Denver International Airport, posted on Twitter stating that after the two girls were barred from the flight.

"She's forcing them to change or put dresses on over leggings or they can't board. Since when does @united police women’s clothing?"

United replied on Twitter by saying, "In our Contract of Carriage, Rule 21, we do have the right to refuse transport for passengers who are barefoot or not properly clothed."

To read United's Contract of Carriage click here.

Watts wrote that three girls in total were inspected for wearing leggings. One of the girls, around 10-years-old, who was wearing gray leggings, as able to cover her leggings with a dress she had with her. Two other girls who did not have a change of clothes were refused boarding altogether.

Watts added that the father of the girl that was able to board, boarded the plane without any issues in his shorts.

Many people voiced their opinion about the situation on Twitter.

@united @PattyArquette you're telling a little girl that dressing comfortably isn't "in good taste"?? I'm reporting on this.— Amelia Edelman (@apedelman) March 26, 2017

United later stated that the girls were flying as pass travelers and that they "Are representing UA when they fly." They continued with a post stating, "We remind all of our employees to review pass travel attire requirements before using their travel privileges."

Jonathan Guerin, a United Airlines spokesperson, later told 9News that yoga pants or leggings are more than welcome for regular paying customers.