WASHINGTON — On Saturday, the comedian Trevor Noah stood before a ballroom of 2,600 journalists, celebrities and political elites at the White House Correspondents Dinner, and asked: What are we doing here?

“Did none of you learn anything from the Gridiron Dinner? Nothing,” Mr. Noah said, referring to another elite Washington gathering in April, after which dozens of attendees tested positive for the coronavirus. “Do you read any of your own newspapers?”

By Wednesday, Mr. Noah’s chiding remarks at what he called “the nation’s most distinguished superspreader event” were beginning to appear prophetic as a growing number of attendees, including a string of journalists and Antony J. Blinken, the secretary of state, said they had tested positive for the virus.

Jen Psaki, the White House press secretary, said on Wednesday that President Biden had tested negative on Tuesday after attending the dinner unmasked. Ms. Psaki added that Mr. Blinken was not considered a close contact to Mr. Biden and “has not seen the president in several days.”

The growing number of cases presented another sign of an official Washington that has largely returned to prepandemic routines, even as officials still urge Americans to take precautions, and has decided to live with the result.

Journalists across several major news organizations reported testing positive. Among those were Jonathan Karl, ABC News’s chief Washington correspondent, who shook hands with Mr. Biden during the dinner, and Steve Herman, the chief national correspondent at Voice of America. CNN reported that those infected also included staff members from its network, as well as NBC News, CBS News and Politico.

It was unclear how many cases had been confirmed as of Wednesday evening. Steven Portnoy of CBS News, the president of the White House Correspondents’ Association, said on Tuesday that the cases he knew of at that time numbered in the “single digits.” Mr. Portnoy did not respond to requests for comment on Wednesday, though reports of new cases continued to grow.

The White House Correspondents Dinner required proof of vaccination and a same-day negative test, and boosters were strongly encouraged. Some of the people reporting infections also said they had attended other gatherings over the weekend.

Attendees of the dinner expressed resignation as the number of confirmed cases grew over the course of the day on Wednesday.

“I’m yet another #WHCA weekend casualty,” Julia Ioffe, a founding partner and Washington correspondent at Puck News, announced on Twitter on Wednesday. “I knew I was taking a risk and, well, here we are!”

Mark Leibovich, a reporter at The Atlantic who attended the dinner and spoke briefly with Mr. Blinken at a gathering the day before, said there had been an expectation that some guests would test positive. He noted that he had tested negative for the virus on Wednesday evening.

“There was kind of a cruise ship vibe” to the dinner, said Mr. Leibovich, who was formerly a reporter at The New York Times. He added that once guests were inside the ballroom, “there was no escape” from the crowds.

Jada Yuan, a reporter at the Washington Post who tested positive on Wednesday after attending the dinner, had said at the time that the ballroom was “like a horror film.”

“No exits. Literally getting trapped between tables,” Ms. Yuan wrote on Twitter. “Fear of breathing near people but people are everywhere. Creeping sense that you’re the only one who know this is insane.”

Many attendees of the event, known as the nerd prom, had undergone a good deal of risk-benefit calculation, considering whether the chance of contracting the coronavirus was worth attending the dinner and its ritzy before- and after-parties.

The Post reported that some White House officials were worried that safety measures for the dinner were insufficient, and that the White House Correspondents’ Association had rebuffed an offer to have a company install — at no charge — devices that disinfect the air using ultraviolet light.

Dr. Anthony S. Fauci, Mr. Biden’s top medical adviser for the coronavirus, said he would not attend the dinner, citing his “individual assessment of my personal risk.” Dr. Fauci was later photographed attending a smaller outdoor pre-party before the dinner on Saturday.