How could a gunman get so close to presidential candidate Donald Trump on Saturday, coming within inches of killing him at a Pennsylvania rally?

That is perhaps the biggest question two days after an assassination attempt that rocked the world and upended the 2024 presidential race.

Some experts are describing the event as an epic security failure, questioning how the gunman could have gotten onto the roof of a building located about a football field’s distance from Trump’s stage and opened fire before being shot by Secret Service agents. Video and eyewitness accounts indicate that some in the crowd noticed the gunman and called out to law enforcement moments before the shooting.

“A direct line of sight like that to the former president should not occur,” Homeland Security Secretary Alejandro Mayorkas told ABC News on Monday.

Others also had questions.

“How could an individual be at that elevation that was seen by apparently bystanders on the ground? How could that not be noticed by Secret Service?” House Speaker Mike Johnson (R-La.) asked Sunday morning on NBC. “Lots more questions than answers this morning,” said Johnson, who has called for a full investigation.

President Biden on Sunday announced an independent review of security at the venue.

The director of the Secret Service, Kimberly Cheatle, said Monday that her agency would cooperate with the investigation and that it is also is trying to determine what happened.

“Secret Service personnel on the ground moved quickly during the incident, with our counter-sniper team neutralizing the shooter and our agents implementing protective measures to ensure the safety of former President Donald Trump,” she said in a statement.

“The Secret Service is working with all involved federal, state and local agencies to understand what happened, how it happened, and how we can prevent an incident like this from ever taking place again. We understand the importance of the independent review announced by President Biden yesterday and will participate fully. We will also work with the appropriate congressional committees on any oversight action.”

Cheatle is already facing questions.

Law enforcement consultant Roy Taylor, who has decades of experience coordinating security details for political events, said securing elevated positions around a venue is key to ensuring a protectee’s safety. He questions why the Pennsylvania rooftop was left open.

“Everybody needs to be taken out of the building, or officers need to be put into the building,” he told The Times. “We need to make sure it’s secured because obviously it’s easier to fire down on somebody than it is for people to fire up, because that gives you a platform of superiority.”

The Secret Service said Trump’s security detail was provided “additional security enhancements” last month and changes were made after Saturday’s assassination attempt “to ensure his continued protection for the [Republican National] Convention and the remainder of the campaign,” Cheatle said in a statement Monday.

Cheatle said she is confident in the agency’s RNC security plans, which have been “reviewed and strengthened in the wake of Saturday’s shooting.”

Trump praised the Secret Service’s action in an interview with the New York Post, saying they came at him like “linebackers” and whisked him to safety.

“The agents hit me so hard that my shoes fell off, and my shoes are tight,” he told the paper.

As for the gunman, “They took him out with one shot right between the eyes,” Trump said. “They did a fantastic job. … It’s surreal for all of us.”

What do we know about the gunman’s location?

Thomas Matthew Crooks, 20, of Bethel Park, Pa., fired an AR-style rifle from atop a building overlooking the rally site.

It is unclear how long he was on the roof.

Videos show that for several minutes, witnesses pointed toward a nondescript roof just outside the venue where Trump was speaking in Butler, Pa. In videos shared on social media, attendees shouted, “He’s got a gun.”

Greg Smith told the BBC that he had seen the shooter crawling on a nearby rooftop before shots rang out. Smith said he and others tried to alert police or the Secret Service to his presence.

“We’re pointing at the guy,” Smith said. “He had a rifle. We could clearly see him with a rifle.”

Smith suspects that law enforcement could not see the man because of the slope of the roof where he was positioned.

A local law enforcement officer spotted Crooks before he began shooting but could not engage him, Butler County Sheriff Michael T. Slupe told CNN. The officer was searching the area after calls were received about a suspicious person outside the rally perimeter, Slupe said. Officers discovered someone was on the roof, and one officer hoisted another up to peer over the ledge.

Crooks turned around, saw the officer and pointed his gun at him, Slupe said. The officer let go to “take cover” and save his own life, the sheriff said.

Law enforcement sources with knowledge of the investigation told The Times that the building was identified as a vulnerability. In such situations, responsibility for security is divided, and local authorities often take a leading role, the sources said. Details of the plan for the rally were not clear.

The shooting

Crooks fired from about 430 feet from the stage where Trump was speaking. Given some training and practice, it would not be a difficult shot to make with an AR-style rifle, said retired Los Angeles Police Department special weapons team officer and sniper Steve Gordon.

“That type of rifle is standard issue to the police/military, and that is not a difficult shot to make with that weapon system,” Gordon said.

Even without seeing the Pennsylvania venue, Gordon said that “it’s nearly impossible, if not completely impossible, to cover every window, rooftop, tree, bush and person.”

“Had they spotted him seconds earlier, they could have shot him immediately based on the circumstances,” he said. “But based on what I’ve seen so far, I believe the counter-sniper team did a tremendous job.”

The Associated Press, which was at the scene, offered this narrative of what happened next:

As the first pop rang out, Trump said, “Oh,” raised his hand to his right ear and looked at it, before quickly crouching behind his lectern. The people in the stands behind him also crouched as screams rang through the crowd.

Someone could be heard near the microphone saying, “Get down, get down, get down, get down!” as agents rushed to the stage. They piled atop the former president to shield him with their bodies as other agents took up positions onstage to search for the threat.

Afterward, voices were heard saying, “Shooter’s down” several times, before someone asked, “Are we good to move?” and “Are we clear?” Then someone ordered, “Let’s move.”

Trump could be heard on the video saying at least twice, “Let me get my shoes,” with another voice heard saying, “I’ve got you, sir.”

Trump got to his feet moments later and could be seen reaching with his right hand toward his face, which was streaked with blood. He then pumped his fist in the air and appeared to mouth the word “fight” twice, prompting loud cheers and then chants of “USA. USA. USA.”

His motorcade left the venue moments later. Video showed Trump turning back to the crowd and raising a fist right before he was put into a vehicle.

While Crooks missed Trump, retired firefighter Corey Comperatore was struck by gunfire while sitting in the bleachers with his family, Pennsylvania Gov. Josh Shapiro said.

On Facebook, Comperatore’s sister, Dawn Comperatore Schafer, described him as a “hero that shielded his daughters” as shots rang out. He had just turned 50, she wrote, and “had so much life left to experience.”

Cheatle extended her condolences to Comperatore’s family and friends Monday, along with the other people who were injured “during this senseless act of violence.”

Growing questions

One big question is whether the Secret Service or local police had secured nearby buildings before Trump began speaking. The building where the shooter was positioned was outside the perimeter of the rally, but experts said officials would typically still secure it.

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

Secret Service spokesman Anthony Guglielmi told the Washington Post that the agency relied on local law enforcement to help with security, but it was unclear who was responsible for that building.

Kevin Rojek, the FBI’s Pittsburgh special agent in charge, said the gun used was an AR-style 556 rifle, which law enforcement officials believe was purchased legally by Crooks’ father. Authorities said it’s unclear how the young man gained access to the weapon.

During the search of the shooter’s car, Rojek said, agents found “a suspicious device,” which was inspected by bomb technicians and rendered safe. Officials said they are investigating the shooting as an assassination attempt and they also are looking at it as a “potential domestic terrorism act.”

The calls for scrutiny over security have come from both Republicans and Democrats.

“Those responsible for the planning, approving and executing of this clearly insufficient security plan need to testify before Congress and be held accountable,” Rep. Ruben Gallego (D-Ariz.) said in a statement.