How could a gunman get close enough to nearly assassinate a former president?

The attempt to assassinate former President Donald Trump at a campaign rally in Pennsylvania on Saturday raised questions about security protocols and how a gunman could open fire so close to the presumptive GOP nominee.

The shooting, which left a spectator dead and injured Trump and at least two others, stunned operatives of both political parties who have seen firsthand the level of precision, care and detail the Secret Service takes in safeguarding its charges. American presidents and former presidents are among the most protected politicians in the world, with multiple layers of security — some visible to the public and others covert.

Democrat Bill Burton saw the intricate level of protection while accompanying then-Sen. Barack Obama during his 2008 campaign and then as a member of his White House administration.

“In the political world, people often ignore the humanity on the other side, but ultimately, former President Trump came within an inch of losing his life today,” said Burton after watching the story unfold live on television monitors during a layover at John F. Kennedy International Airport in New York. “And regardless of what these next months and years hold, I don’t think any of us want to live in a country where that is a reality for our leaders.”

At campaign rallies and official White House events, the level of security for spectators is greater than at an airport checkpoint. Items as innocuous as umbrellas are often confiscated. For reporters and others in close proximity to the president or a prominent candidate, the security is even more in-depth, with background checks and trained dogs smelling bags and equipment.

[Trump injured in shooting at rally, gunman and 1 attendee are dead]

In addition to such publicly visible efforts, agents are often perched on rooftops with long guns when a protectee appears in public. Motorcades are guarded by federal, state and local law enforcement. Buildings and event sites are screened and safeguarded in advance, and intelligence about potential threats is vetted.

The assassination attempt took place on the cusp of the Republican National Convention in Milwaukee, which starts Monday, with Trump expected to accept his party’s nomination on Thursday.

Security during such events is extraordinarily tight and is certain to grow stricter after what occurred on Saturday.

Wisconsin Gov. Tony Evers, a Democrat, said he and his staff are communicating with the agencies coordinating security for the event.

“We cannot be a country that accepts political violence of any kind — that is not who we are as Americans,” Evers said on the social media platform X.

As Trump addressed supporters on Saturday, shots rang out. The former president clapped his hand to the side of his face and ducked, with Secret Service agents quickly surrounding him and whisking him away as blood dripped near his right ear.

One spectator was killed and two were critically injured. The shooter, perched on a rooftop outside the event perimeter, was killed by Secret Service agents, according to the Associated Press and other media outlets.

“Quite frankly, I don’t know how he would have gotten to the location where he was, but he was outside the grounds,” Butler County District Attorney Richard A. Goldinger told CNN. “And I think that’s something that we’re gonna have to figure out how he got there.”

“We haven’t seen this since Reagan,” he added. “It’s mind blowing. You know, maybe we got a little lackadaisical about it, that this wouldn’t happen to a president or a former president. But it’s crazy. Sadly, maybe it’s just the state of our current political situation.”

The last publicly known assassination attempt of a president or former president occurred in 1981 when Ronald Reagan was shot and seriously injured as he left a hotel in Washington, D.C.

An adviser to 2012 GOP presidential nominee Mitt Romney said the danger grows exponentially at outdoor events, which he described as “the most difficult.”

“So many ways to get a weapon in. Could have been tossed over a fence. Dug into the ground and placed earlier. Who knows?” said the adviser, asking not to be identified to speak candidly about the situation.

Burton said that while the Secret Service offers “the best protection in the world … any security official would tell you that it is nearly impossible to stop a committed lone wolf who is willing to die for his cause.”

Obama received Secret Service protection earlier than any presidential candidate in history because of the level of threats against him.

“I was absolutely shocked and immediately saddened,” said Burton of Saturday’s violence.

The Secret Service was charged with protecting presidents in 1902 after the assassination of President William McKinley the previous year. Its duties — safeguarding the nation’s leaders and their families — have grown over the years, most significantly after the assassination of President John F. Kennedy in 1963.