Oklahoma health officials expressed concern before President Trump’s indoor rally in June, warning there could be sizable spikes in COVID-19 cases and deaths from the event, internal documents and emails obtained by The Hill showed Wednesday.

The emails revealed growing angst within the Oklahoma public health department in the days leading up to the June 20 rally. Aaron Wendelboe, who at the time was the Oklahoma State Department of Health’s epidemiologist, sent one email with the subject line: “How strongly do I speak out?”

“I am concerned that the mass indoor gathering in Tulsa of 19,000 people will directly lead to deaths in Oklahoma,” Wendelboe wrote in the email. “As the state epidemiologist, I feel I have a responsibility to speak out and warn of the estimated risk.”

A risk analysis conducted by Wendelboe estimated the rally would likely lead to “at least 2 deaths and probably closer to 10.”

Five days before the event, in a separate email to Tulsa Health Department Director Bruce Dart, Wendelboe wrote: “I’m not sure of any instance where we would hold a public event and say, ‘And by the way, there is a chance that attending this could lead to a minimum of two deaths.’”

Dart on June 13 called for the rally to be postponed, and Wendelboe left the department after his contract expired several weeks later.

Eight days before the rally, the Tulsa Health Department “reported its highest daily increase of COVID-19 cases to date,” a June 12 press release said. Dart is quoted as saying, “I have concerns about large groups of people gathering indoors for prolonged lengths of time.” The department stressed the need for people to cover their faces at such gatherings.

Some 6,200 people attended the rally, and Trump's speech was held inside despite health officials' concerns . It’s unclear how many coronavirus cases can be linked to the rally though two weeks after it took place, Dart said it had “more than likely contributed” to a jump in cases.

Herman Cain, who ran for president in 2012, attended the event and did not wear a mask. He was hospitalized nearly two weeks later and died of complications from COVID-19 on July 30 at the age of 74.

Trump campaign staffers working at the rally tested positive for COVID-19 and were quarantined, a June statement from the campaign said.

On Sunday, the Trump campaign held an indoor rally in Nevada, the first since the Tulsa gathering. The event attracted criticism from public health experts, but the Trump campaign defended it, saying public health precautions were taken.

“If you can join tens of thousands of people protesting in the streets, gamble in a casino, or burn down small businesses in riots, you can gather peacefully under the First Amendment to hear from the president of the United States,” Tim Murtaugh, Trump’s 2020 communications director, said in a statement.

Xtreme Manufacturing, the Nevada company that hosted the indoor rally faces a $3,000 fine for violating state coronavirus guidelines banning large gatherings, CNN reported.

"During the event, a compliance officer observed six violations of the directives and the city's Business Operations Division has issued a business license notice of violation to Xtreme Manufacturing and assessed a penalty of $3,000," Kathleen Richards, senior public information officer for the city of Henderson, told CNN in a statement Monday.