The man suspected of opening fire on the Centers for Disease Control and Prevention’s sprawling campus late Friday had blamed the COVID-19 vaccine for making him sick and depressed, according to information gathered by law enforcement and sources close to the suspect.

The investigation remains ongoing, and officials caution that the information is preliminary at this time.

Patrick White is believed to have struggled with his mental health, according to that information. As he grappled with those issues, sources said, White had become increasingly fixated on the COVID-19 vaccine as a source of his grievances.

Several Kennesaw residents who knew the 30-year-old suspected shooter told ABC News they had heard White express similar angry and conspiracy-minded sentiments.

One neighbor, who asked not to be named, said White would sit on her porch for long stretches, often complaining that after he got the COVID-19 shot, he had lost a lot of weight, developed problems swallowing and gastrointestinal issues. And, the neighbor said he believed the media and government weren’t covering it.

“He thought the vaccines were killing him and that people needed to know the truth,” the neighbor said, adding that she didn’t agree with him, but would listen.

White’s father declined to comment on his son when reached by ABC News.

The Georgia Bureau of Investigation, which is leading the probe, declined to comment on a potential motive.

Infectious disease experts maintain that mRNA vaccines like those used against COVID-19 have been studied for decades and that the shots were instrumental in saving lives during the COVID-19 pandemic, according to the CDC. Though the COVID-19 vaccines have been highly politicized and subject to a deluge of mis and disinformation, experts say they are safe and effective.

Long-term adverse reactions to the COVID-19 vaccines are generally very rare, according to the CDC.

All CDC employees nationwide, except for essential on-site personnel, have been instructed to work remotely on Monday as Georgia investigators continue probing Friday’s deadly active shooter incident near the agency’s Atlanta headquarters, according to a letter obtained by ABC News.

In the letter, CDC leadership told the agency’s more than 10,000 employees that both federal and local law enforcement are conducting “intensive monitoring of all potential threats to CDC and its staff, current and past” to ensure their safety.

Investigators have yet to reveal the motive behind Friday’s shooting, but the CDC leadership said in the email, “What we know about the incident is that this was a targeted attack on CDC related to COVID.”

DeKalb County Police Officer David Rose was fatally shot after responding to the reported gunfire.

He was taken to the hospital in critical condition, where he was pronounced dead, officials said at a press conference Friday evening.

During the shooting, the suspect fired multiple rounds at CDC buildings, breaking windows, Atlanta Police Chief Darin Schierbaum said during a press conference.

In the aftermath of the shooting, four other people were transported to an area hospital for stress and anxiety-related reasons, the police chief said.