Three House Republicans each must pay $500 fines imposed by the sergeant-at-arms for being warned and then failing to wear a mask on the House floor.

Reps. Brian Mast of Florida, Beth Van Duyne of Texas and Mariannette Miller-Meeks of Iowa were all fined, according to an announcement released on Friday by the House Ethics Committee.

The three were among 10 Republicans who defied House rules in May requiring the wearing of masks on the floor at the time. Warnings were issued, with the rules providing for fines in the event of a second offense.

Mast and Van Duyne unsuccessfully appealed and Miller-Meeks did not file an appeal to the Ethics panel over the infractions. Unless a majority of the bipartisan 10-member committee agrees to the appeal, it is rejected.

Subsequent offenses come with a $2,500 fine.

Although several members have publicly announced their defiance of the House mask mandate, the three are the first to be announced by the Ethics Committee.

They might be the only ones to face such fines. As of June 11, the Office of the Attending Physician, led by Brian P. Monahan, announced that people fully vaccinated against COVID-19 need not wear masks in the House chamber.

Mast noted in his appeal that he “was in full compliance with Center[s] for Disease Control and Prevention (CDC) guidance,” adding that he is “fully vaccinated and followed the science.” This is a reference to updated CDC guidance issued in May that fully vaccinated people need not social distance or wear a mask.

After the CDC made public that guidance, Speaker Nancy Pelosi said she would not lift the mandate until more members were vaccinated, citing low rates among House Republicans.

Van Duyne also cited the CDC guidance in her appeal and said Pelosi and other Democrats were at a recent White House events without masks on. The White House has been more strict about COVID-19 protocols for staff, visitors and press since Joe Biden was inaugurated.

“It’s evident now that enforcement of any mask rule has become a partisan, political issue, rather than one grounded in science,” she wrote. “Masks are now a political statement to which I object, and requiring me to wear one violates my First Amendment rights under the United States Constitution.”

Niels Lesniewski contributed to this report.