On the heels of an apparent attempt to kill him, former President Trump called Sunday for unity and resilience as shocked leaders across the political divide recoiled from the shooting that left him injured but “fine” and the gunman and a rally-goer dead.

The presumptive Republican presidential nominee said the upper part of his right ear was pierced in the shooting. His aides said he was in “great spirits” and doing well.

“I knew immediately that something was wrong in that I heard a whizzing sound, shots, and immediately felt the bullet ripping through the skin,” he wrote on his social media site. “Much bleeding took place.”

In a subsequent post Sunday, Trump said “it was God alone who prevented the unthinkable from happening.”

“In this moment, it is more important than ever that we stand United, and show our True Character as Americans, remaining Strong and Determined, and not allowing Evil to Win,” his post said.

The FBI early Sunday identified the shooter as Thomas Matthew Crooks, 20, of Bethel Park, Pa.

Secret Service agents fatally shot Crooks. The gunman attacked from an elevated position outside the rally venue at a farm show in Butler, the agency said.

One attendee was killed and two spectators were critically injured, authorities said. All were identified as men.

Investigators believe the weapon had been purchased by Crooks’ father at least six months ago, two law enforcement officials said. Federal agents were still working to understand when and how his son obtained the gun and to gather additional information about Crooks as they worked to try to identify a motive, the officials said.

The officials were not authorized to publicly discuss details of the investigation and spoke to the AP on condition of anonymity.

Crooks’ political leanings were not immediately clear. Records show Crooks was registered as a Republican voter in Pennsylvania, but federal campaign finance reports also show he gave $15 to a progressive political action committee on Jan. 20, 2021, the day President Biden was sworn in to office.

Authorities told reporters that Crooks was not carrying identification so they were using DNA and other methods to confirm his identity. Law enforcement recovered an AR-style rifle at the scene, according to a person familiar with the matter who spoke on condition of anonymity to discuss the investigation.

The attack was the most serious attempt to kill a president or presidential candidate since Ronald Reagan was shot in 1981. It drew new attention to concerns about political violence in a deeply polarized U.S. less than four months before the presidential election. And it could alter the tenor and security posture at the Republican National Convention, which will begin Monday in Milwaukee.

Organizers said the convention would proceed as planned.

Trump flew to New Jersey after visiting a local Pennsylvania hospital, landing shortly after midnight at Newark Liberty International Airport. Video posted by an aide showed the former president leaving his private jet flanked by U.S. Secret Service agents and heavily armed members of the agency’s counter assault team, an unusually visible show of force by his protective detail.

Biden, who is running against Trump, was briefed on the attack and spoke to Trump several hours after the shooting, the White House said.

“There’s no place in America for this type of violence,” the president said in televised remarks. “It’s sick. It’s sick.”

Biden planned to return to Washington early, cutting short a weekend at his beach home in Rehoboth Beach, Del.

Many Republicans quickly blamed the violence on Biden and his allies, arguing that sustained attacks on Trump as a threat to democracy have created a toxic environment. They pointed in particular to a comment Biden made to donors on July 8, saying “it’s time to put Trump in the bull’s-eye.”

Officials said members of the Secret Service counter-assault team killed the shooter. The heavily armed tactical team travels everywhere with the president and major party nominees and is meant to confront any active threats while other agents focus on safeguarding and evacuating the person at the center of protection.

An AP analysis of more than a dozen videos and photos from the scene of the Trump rally, as well as satellite imagery of the site, shows the shooter was able to get astonishingly close to the stage where the former president was speaking.

A video posted to social media and geolocated by the AP shows the body of a person wearing gray camouflage lying motionless on the roof of a building at AGR International, a manufacturing plant just north of the Butler Farm Show grounds where Trump’s rally was held.

The roof where the person lay was less than 150 meters, or 164 yards, from where Trump was speaking, a distance from which a decent marksman could reasonably hit a human-sized target. For reference, 150 meters is a distance at which U.S. Army recruits must hit a scaled human-sized silhouette to qualify with the M-16 rifle. The AR-15, like the shooter at the Trump rally had, is the semi-automatic civilian version of the military M-16.

Asked at the news conference whether law enforcement did not know the shooter was on the roof until he began firing, Kevin Rojek, special agent in charge of the FBI’s Pittsburgh field office, responded that “that is our assessment at this time.”

“It is surprising” that the gunman was able to open fire on the stage before the Secret Service killed him, he added.

Homeland Security Secretary Alejandro Mayorkas, whose department oversees the Secret Service, said officials were engaged with the Biden and Trump campaigns and “taking every possible measure to ensure their safety and security.”

A rally disrupted by gunfire

Trump was showing off a chart of border crossing numbers when the gunfire began after 6:10 p.m.

As the first pop rang out, Trump said, “Oh,” and raised his hand to his right ear and looked at it, before quickly crouching to the ground 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 is their training protocol, as other agents took up positions on stage to search for the threat.

Screams were heard in the crowd of several thousand people. 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, 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 to his crowd of supporters, 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.

Witnesses heard multiple gunshots and ducked for cover

“Everybody went to their knees or their prone position, because we all knew, everyone becoming aware of the fact this was gunfire,” said Dave McCormick, the Republican candidate for U.S. Senate in Pennsylvania, who was sitting to Trump’s right on stage.

As he saw Trump raise his fist, McCormick said, he looked over his shoulder and saw someone had been hit while sitting in the bleachers behind the stage.

Eventually, first responders were able to carry the injured person out of the large crowd, McCormick said.

Reporters covering the rally heard five or six shots ring out and many ducked for cover, hiding under tables. After the first two or three bangs, people in the crowd looked startled, but not panicked. An AP reporter at the scene reported the noise sounded like firecrackers at first or perhaps a car backfiring.

When it was clear the situation had been contained and Trump would not return to speak, attendees started filing out of the venue. One man in an electric wheelchair got stuck on the field when his chair’s battery died. Others tried to help him move.

Police soon told the people remaining to leave the venue and Secret Service agents told reporters to get “out now. This is a live crime scene.”

Two firefighters from nearby Steubenville, Ohio, who were at the rally told the AP that they helped people who appeared injured and heard bullets hitting broadcast speakers.

“The bullets rattled around the grandstand, one hit the speaker tower and then chaos broke,” Chris Takach said. “We hit the ground and then the police converged into the grandstands.”

“The first thing I heard is a couple of cracks,” Dave Sullivan said.

Sullivan said he saw one of the speakers get hit and bullets rattling and, “we hit the deck.”

He said once Secret Service and other authorities converged on Trump, he and Takach helped two people who may have been shot in the grandstand and cleared a path to get them out of the way.

“Just a sad day for America,” said Sullivan, who described fluid spraying from a mechanical line on the stage before a speaker tower started to fall.

“Then we heard another shot that, you could hear, you knew something was — it was bullets. It wasn’t firecrackers.”

Political violence again shakes America

The perils of campaigning took on a new urgency after the assassination of Robert F. Kennedy in California in 1968, and again in 1972 when Arthur Bremer shot and seriously hurt George Wallace, who was running as an independent on a campaign platform that has sometimes been compared to Trump’s. That led to increased protection of candidates, even as the threats persisted, notably against Jesse Jackson in 1988 and Barack Obama in 2008.

Presidents, particularly after the assassination of John F. Kennedy in 1963, have even greater layers of security, and Trump is a rarity as both a former president and a current candidate.

North Dakota Gov. Doug Burgum, Florida Sen. Marco Rubio and Ohio Sen. J.D. Vance, three men on Trump’s short list for vice president, all quickly sent out statements expressing concern for the former president, with Rubio sharing an image taken as Trump was escorted off stage with his fist in the air and a streak of blood on his face along with the words “God protected President Trump.”

Carr Smyth, Colvin, Long, Balsamo, Tucker and Price write for the Associated Press. Colvin, Balsamo and Price reported from New York, Long from Washington and Tucker from Westport, Conn. AP writers Michael Biesecker and Alanna Durkin Richer in Washington, Marc Levy in Harrisburg, Pa., and Will Weissert in Rehoboth Beach, Del., contributed to this report.