The first US Open women's semifinal between Coco Gauff and Karolina Muchova was halted in the second set after what appeared to be protesters in the crowd disrupted play.

The US Open called it a "fan-related" incident, according to a statement, and said one attendee "affixed himself to the floor and due to the nature of this action, medical professionals, NYPD and security personnel were needed in order to resolve the issue and remove the fan from the stands."

As the attendee -- who was shouting about "environmental issues," according to the ESPN broadcast -- was removed, the fans on hand at Arthur Ashe Stadium cheered.

Gauff and Muchova had left the court during the pause, then returned and play eventually resumed after more than a 45-minute delay.

US Tennis Association chief executive Stacey Allaster told the ESPN broadcast there were three protesters and two were "quietly removed." The other protester glued their bare feet to the floor, Allaster added.

"There's no doubt in a 24,000-seat stadium, hopefully, people don't get ideas," Allaster said. "We know in these large events, environmental protestors use the platform. Certainly, security will be resuming -- along with NYPD -- to see what we can do to prevent it in the future."

This is a developing story and will be updated.