MIAMI (AFP) - Police in Florida have arrested a man who threatened to go on a shooting rampage in his local supermarket because he thought too few shoppers were wearing protective masks against the coronavirus.

Robert Kovner, 62, was arrested after he posted on Facebook that he would "empty every clip I own" in his local Publix supermarket because not enough of the customers were wearing protective face coverings, police said.

"Will it take shooting a few of you selfish a-holes in the parking lot to get the message through?" Kovner was reported to have posted on social media.

"Trust me the virus is not the only thing that may cause your demise!"

Police in Sebring, some 135km south of Orlando, said that "these are stressful times, but there is no excuse for making threats like this."

"It's not a joke. It's not just a bad day. It's a crime. We will ALWAYS take them seriously and you will go to jail," they said.

Florida has some of the laxest gun laws in the United States, a country rife with mass shootings and where the right to possess guns is guaranteed by the constitution.

Gun shops have been listed as essential services during the pandemic and have racked up record sales since March.

Following federal guidelines, Florida recommends the use of masks in public spaces to prevent the spread of the disease, but face coverings are not obligatory outside of cities like Miami and Miami Beach, whose mayors have ordered them to be worn in enclosed spaces that are open to the public.

By Friday, Florida had recorded more than 24,000 cases of coronavirus, with 680 deaths.

Kovner was charged with threatening to carry out a mass shooting and slapped with a US$30,000 (S$50,000) bail, according to the Miami Herald newspaper.