Anti-mask activists organised a protest at a grilled cheese restaurant in Florida after the owner encouraged people not to wear masks.
The US restaurant 33 & Melt has created tension after the owner, Carrie Hudson, promised 100 free meals for those who turn up without a mask on July 11.
During Saturday's protest, no customers wore face coverings inside the restaurant, despite the fact Florida county officials made the use of face masks in public mandatory since June 20.
The rally became tense when the Florida Division of Alcoholic Beverages and Tobacco arrived at the restaurant and served Hudson with a warning.
"It's wrong, it's wrong, it's wrong. Don't shut her down, don't shut her down," protesters responded in a Global News video.
Protester Chris Nelson said in the video, "All she is doing is standing up for the rights of people to make their own medical decisions".
"You know what, you wanna call me selfish for not wearing a mask? I wanna say to you, all the people call me selfish, you're the one who's trying to force me [to have] a medical procedure so YOU can feel more safe," he said.
Many Americans still refuse to wear a mask even though health experts say the use of face masks may help stop transmission of the virus.
Another anti-mask activist said she did not oppose those who want to wear face masks.
"If you are at higher risk, feel free to stay home, feel free to wear a mask, feel free to social distance - that is your choice and we respect it. We want our choices to be respected as well," said Tara Hill.
Florida has reported the largest single-day increase of COVID-19 of any state in the US, with a total of more than 269,000 confirmed cases so far.
According to the state Department of Health statistics, Florida reported an increase of more than 15,000 new cases of COVID-19 in 24 hours on Sunday, the day after the protest.
US President Donald Trump wore a face mask for the first time in public when he visited a Washington DC-area military hospital on Saturday July 12.
He had previously refused to wear a face mask or asked residents to wear one, saying it was a personal choice.