Donald Trump Jr. said he was fishing with his daughter on Saturday when his fiancée, Kimberly Guilfoyle, called to tell him that his father was shot.

"Kim calls me [and said], 'Your father was shot,'" Trump Jr. recounted during a fireside chat with Axios.

But she had no other information to give, he said.

"It was 90 minutes before I even knew he was alive," Trump Jr. said.

Trump Jr. said then he was able to speak to his father on the phone.

"Considering the heaviness of that moment, sort of gave me a window for some levity and. you know, I asked him, 'Well, most importantly, like, how's the hair?'" he said.

Trump Jr. said his father responded, "The hair is fine ... a lot of blood in it, but it's fine."

"It was a heavy couple of hours, just that unknown," Trump Jr. said. "And then you finally find everything's OK, and then you sit down, and you start seeing the video when you're watching the news. And it was like, the adrenaline dump leaves, you know. Sort of amazing how calm I was first, and then, it's like, once that goes -- 'poof.'"

Trump Jr. said he believes his father is a changed man after the shooting.

"There are events that change you for a couple minutes and there's events that change you permanently," he said.

He also said he believes that there was a breach in security procedures at Saturday's rally.

The U.S. Secret Service in recent weeks had increased Donald Trump's security detail due to intelligence indicating there was an Iranian threat to assassinate the former president, according to three officials familiar with the matter.

There is no indication the plot was related to the assassination attempt against the former president on Saturday.

The sources have suggested Iran has been making these types of threats since the assassination of Iranian military officer Qasem Soleimani in January 2020.

READ MORE | Trump Secret Service protection had been increased due to Iran threat

Trump's campaign announced that he and JD Vance will be holding a rally in Grand Rapids, Michigan, on Saturday.

This will mark their first rally together and the first one after Trump's assassination attempt. The rally will take place in an indoor venue and the first since the assassination attempt on Saturday.

The Department of Homeland Security and the FBI have issued a bulletin to law enforcement across the country warning them that, in the wake of Saturday's attempted assassination of former President Donald Trump, violent extremists could try to conduct "follow-on or retaliatory" attacks at events over the next few months related to the 2024 presidential election.

The bulletin urged local, state and federal law enforcement -- and their partners -- to remain vigilant and report any suspicious behavior.

"The FBI and DHS remain concerned ... particularly given that individuals in some online communities have threatened, encouraged, or referenced acts of violence in response to the attempted assassination," said the bulletin, issued Monday night as the Republican National Convention got underway in Milwaukee to officially nominate Trump as the Republican Party's candidate for the White House in November.