The shimmering low-rise metal and glass towers at the headquarters of the Centers for Disease Control and Prevention in Atlanta were pocked with dozens of bullet holes. Cracks streaked windows. Shell casings littered a sidewalk across the street.

Law enforcement officials said that Patrick Joseph White, a 30-year-old from the suburbs of Atlanta, opened fire on the complex of buildings on Friday afternoon. He had become fixated with the coronavirus vaccine, believing that it was the cause of his own physical ailments, officials said, and he attacked the institution that has been at the center of rampant conspiracy theories and misinformation about the federal government’s response to the pandemic.

Mr. White was found fatally shot, although it was unclear if he had been killed in an exchange of gunfire with the police or it was self-inflicted, police officials said. An officer from the DeKalb County Police Department — a rookie not even a year into the job — was killed.

Investigators on Saturday were piecing together Mr. White’s history, trying to understand what precipitated the spray of gunfire.

Five guns were recovered at the scene, according to a preliminary internal report on the investigation from the Justice Department. Four of the weapons were long guns, and at least one of the weapons was equipped with a scope, according to the report, which was reviewed by The New York Times.

The attack has provoked alarm and outrage from the community of public health officials and workers whose efforts have been maligned and politicized. They argue that the shooting was a manifestation of false information that has surrounded the vaccine and animosity directed at the agency. .

“The cruel irony is that this gunman threatened the lives of the very people who are dedicated to improving public health and safety, including violence prevention,” said Dr. Ina Park, an infectious diseases physician at the University of California, San Francisco, who works with the C.D.C. on guidelines for sexually transmitted diseases and frequently visits the headquarters.

In a message to C.D.C. employees sent on Friday night, Susan Monarez, who was confirmed last month as the agency’s director, said the shooting has “understandably brought fear, anger and worry to all of us.”

Robert F. Kennedy Jr., the health and human services secretary, also acknowledged “how shaken our public health colleagues feel today” in a statement on Saturday morning.

Officials reported an active shooter just before 5 p.m. at a CVS drugstore on Clifton Road, which is directly across from the main entrance to the C.D.C. headquarters. Officers found the gunman on the second floor of the CVS. At least four buildings on the C.D.C. campus were struck by gunfire. One photograph shared by an employee showed one of the buildings had at least 18 bullet holes.

Some, if not all, of the guns were owned by Mr. White’s father, Kenneth White, who had legally obtained them, according to the Justice Department report. When approached by a reporter outside the home where Mr. White lived with his father, Kenneth White declined to comment.

The officer who was killed, David Rose of the DeKalb County Police Department, was one of the first to respond to the shooting. Officer Rose, 33, had just finished his training in March, after serving in the U.S. Marines. He was married with two children, and his wife is expecting a third.

The attack struck an institution that is core to Atlanta’s identity, helping transform the city into a capital of public health work. The headquarters are in the northeast corner of the city, adjacent to the main campus of Emory University and Emory University Hospital.

The sudden burst of violence added an unsettling new chapter to what had already been a turbulent period for the agency and its employees. The Trump administration has moved aggressively to restructure the C.D.C., regarded as the world’s premier public health agency, and pursued extensive layoffs of health workers that have threatened to curtail its scope and influence.

“We know that you’ve had a tough go of it for the past year,” Mayor Andre Dickens of Atlanta, a Democrat, said at a news conference on Friday evening. “We stand with you.”

The creation of the coronavirus vaccines was an achievement that limited the spread of a deadly global pandemic but also became the subject of rampant conspiracy theories and intense political divisions.

Mr. Kennedy has been a prominent voice raising doubts about Covid vaccinations, as well as many routine immunizations. He has made provocative statements — including calling the Covid vaccine the “deadliest” ever made — that directly contradict evidence that has shown the shot to be overwhelmingly effective.

This week, Mr. Kennedy canceled nearly $500 million in grants and contracts for work on mRNA vaccines, the technology that helped turn the tide against the coronavirus.

Critics of Mr. Kennedy argued that he also helped fuel the animosity directed at the C.D.C. Federal officials have blamed the agency for botching the country’s response to the Covid-19 pandemic. Mr. Kennedy has previously called the C.D.C. a “cesspool of corruption,” and a fascist enterprise. He accused C.D.C. employees of covering up vaccine harms to children, comparing it to the Catholic Church’s coverup of child sex abuse.

The shooting was “just the perfect, terrible metaphor for what public health has endured these past six months — and the past six years,” said Katelyn Jetelina, a public health expert who has worked closely with the C.D.C.

In his statement on Saturday, Mr. Kennedy said that public health workers needed recognition and support. “No one should face violence while working to protect the health of others,” he said, adding, “Public health workers show up every day with purpose — even in moments of grief and uncertainty.”

Law enforcement officials searched the house where Mr. White lived with his parents in Kennesaw, a suburb northwest of Atlanta, some 30 miles from the C.D.C. headquarters.

In a neighborhood of winding streets lined with trees, sprawling yards and spacious homes, Mr. White was mostly known for quietly pitching in. He helped with handiwork, mowed lawns, trimmed hedges and walked dogs — sometimes for pay, sometimes not.

But some neighbors had noticed a shift in him. Nancy Hoalst, who lives across the cul-de-sac from the Whites’ beige two-story house, said he had become “unsettled.”

“He very deeply believed that vaccines had hurt him,” Ms. Hoalst said, “and that they were hurting other people.”

His apparent obsession with anti-vaccine conspiracy theories seemed to come out of nowhere about a year ago, she said. Mr. White would launch into unrelenting monologues about it on her front porch, describing a vast and confusing conspiracy.

She would just let him talk, finding it unwise to acknowledge that she herself was vaccinated. But, she added, she “never thought he would take it out on other people.”

“It was a such a belief, it was almost like faith,” Ms. Hoalst said of his obsession with the vaccine. “It was a tenet of who he was.”

Andy Newman and Christina Morales contributed reporting. Susan C. Beachy and Sheelagh McNeill contributed research.