Unlike the shooting at Trump's rally in July, his presence at the golf course on Sunday wasn't planned or announced ahead of time.
The Secret Service has made security changes to the course since the first attempt on Trump's life.
ABC7 News turned to experts on politics and protecting presidents to put this shocking incident in context.
"Never a dull moment in election 2024," said Melissa Michelson, Dean of Arts & Sciences and Professor of Political Science at Menlo College.
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It's the second time in two months there's been an apparent attempt on the former president's life.
"The unprecedentedness of this is more that it's about somebody trying to take somebody out before the election happens. Whereas, usually when we see these kinds of high level assassination attempts, it's about somebody who's already in office," Michelson said. "It's also a sad commentary on the degree to which we are so polarized, that people are so invested in the outcome of this election or are so angry about one of the people running, that they think it might be appropriate to try to assassinate that person."
Secret Service officials Sunday described the agents actions.
"He noticed that the rifle was pointed out. Our agents engaged. We are not sure right now if the individual was able to take a shot at our agents," said Rafael Barros, representative for the U.S. Secret Service.
MORE: Motive still a mystery in Trump assassination attempt, FBI says
"Kudos to them for preventing a tragedy upon the former president or anybody else involved," said Cory Allen, former Secret Service agent. "The Secret Service agents who were out there on the golf course with them were doing their jobs and did it really well to the point of spotting something, which many others wouldn't see, would be part of a rifle barrel sticking out of a fence," Allen said, adding Trump is redefining what it means to protect a former president.
"Normally in the past, as we've all seen, former presidents just kind of fade into the background and go about painting things in Texas or creating foundations to do great things for the world. So the dynamics very much changed with former President Trump," he said.
Meanwhile, as for how this latest assassination attempt could impact the election:
"People who support Trump and want him to win and who are upset that he's the target of assassination attempts are going to now send in more money, are going to be more determined to elect him," Michelson said.