4 teachers died of COVID-19 within 24 hours in Broward County, Florida. Schools there are defying Gov. DeSantis' ban on mask mandates.

• Four teachers from Florida's Broward County died from COVID-19 on Tuesday and Wednesday.
• One taught high school; another elementary school. The other two were from the same school.
• This week, Broward County's school board voted to defy a ban on mask mandates on school premises.

Three teachers and a teaching assistant in Florida's Broward County died from COVID-19 within a span of 24 hours, the Broward Teachers Union told NBC Miami on Thursday.

The union's president, Anna Fusco, said at least three of the four were unvaccinated, per NBC Miami. All four were on summer break when they caught the virus and died just as the school year was about to begin, she added.

Fusco told CBS Miami that one was a high-school teacher, another taught in elementary school, and the teaching assistant and the remaining teacher were from the same school. "It's extremely frightening," she said. "I hear this every day. Whether in Broward or elsewhere. We're the fifth-largest union in the country."

She told NBC Miami: "It really hits because we've been in this conversation about masking up in schools, our own elected governor acting like masks are not necessary."

Broward County is located in southeastern Florida and includes Fort Lauderdale. Earlier this week, the Broward County Public Schools board defied Gov. Ron DeSantis' ban on mask mandates. They voted 8-1 to require staff members and students to wear face coverings amid a record-breaking spike in the state's coronavirus cases.

"Bring it," said one board member, Nora Rupert, after DeSantis threatened to withhold paychecks of school officials who made masks mandatory.

A representative for DeSantis previously told Insider's Connor Perret that DeSantis wanted to protect parents' rights to choose whether their kids should wear masks.

A school district in Marion County, which is located four hours from Broward, northwest of Orlando, reported Friday that four members of its teaching staff had also died from COVID-19 over the summer.

In July, DeSantis issued an executive order banning mask mandates for Florida public schools, despite rising cases among children in the state. Earlier this week, more than 800 Florida physicians signed an open letter to DeSantis urging him to revise his policy.

"This past week, COVID-19 has infected more than 19,000 Floridians every day, the worst weekly infection rate since the pandemic began, and hospitalized an average of 1,800 Floridians daily," the letter said. "In the last week of July, at least 35 children were hospitalized every day for COVID-19 in Florida, a number that is very likely an undercount since Gov. DeSantis stopped sharing COVID-19 statistics."

Rather than issue mask mandates, DeSantis has rolled out a program to provide a monoclonal-antibody treatment from the company Regeneron through clinics - one of the treatments then-President Donald Trump was said to have received when he tested positive for COVID-19.