Coronavirus Updates: Latest News and Analysis

“Six members of the advance team tested positive out of hundreds of tests performed, and quarantine procedures were immediately implemented,” said a campaign spokesman, Tim Murtaugh. “No Covid-positive staffers or anyone in immediate contact will be at today’s rally or near attendees and elected officials.”

Mr. Trump, made aware of the sick campaign aides before departing for the rally, was incensed the news was made public, according to two people familiar with his reaction.

There have been at least 10,037 cases of the coronavirus in Oklahoma, according to a New York Times database. As of Saturday afternoon, at least 368 people had died.

Tulsa health officials have expressed concerns that the rally, in a large, indoor arena, has the potential to become a “superspreader” event. But Trump supporters gathered in Tulsa appeared less worried about the virus and more exuberant over the president’s return to the campaign trail. A few hundred gathered at Fourth and Cheyenne, the first rally checkpoint. Almost none wore masks.

“If it is God’s will that I get coronavirus, that is the will of the Almighty,” said Robert Montanelli, a resident of a Tulsa suburb. “I will not live in fear.”

“I don’t feel sick,” said Mike Pellerin of Austin, Texas, who wore a T-shirt saying “Are we dead yet?” and proudly noted his age, 68. “I don’t have the virus. I’m not going to give it to anyone.”

The campaign stressed that all rally attendees are receiving temperature checks before going through security, and are then given wristbands, face masks and hand sanitizer. Kayleigh McEnany, the White House press secretary, said on Friday that using the masks would be optional. Mr. Trump has eschewed masks in public, and Ms. McEnany said that she would not wear one at the rally.