Details have slowly emerged in the 24 hours since former President Donald Trump was shot during a campaign rally in Pennsylvania on Saturday. 

The suspected shooter was identified by the FBI as Thomas Matthew Crooks, 20, who was killed shortly after opening fire. 

Trump was speaking to supporters in the Pittsburgh suburb of Butler about President Biden's immigration record when shots rang out a few minutes into his speech. Trump was seen clutching his ear after what sounded like gunshots were heard. 

Secret Service agents immediately swarmed the former president from all sides after rushing onstage. Onlookers were surprised and screams could be heard from the crowd. 

SHOOTING AT TRUMP RALLY BEING INVESTIGATED AS ASSASSINATION ATTEMPT

Donald Trump gestures with a bloodied face as multiple shots rang out during a campaign rally

Republican presidential candidate and former President Donald Trump is assisted by security personnel after gunfire rang out during a campaign rally at the Butler Farm Show in Butler, Pennsylvania, July 13, 2024. (REUTERS/Brendan McDermid)

The agents helped Trump from the ground before he raised his fist to the crowd, which elicited cheers from supporters. He was helped offstage and placed in a vehicle. 

Trump was left largely unharmed, but one spectator, Corey Comperatore, 50, of Sarver, Pennsylvania, died and two others, David Dutch, 57, and 74-year-old James Copenhaver, were wounded; both were listed in stable condition, the Pennsylvania State Police said Sunday. 

Donald Trump reacts as multiple shots rang out during a campaign rally

Republican presidential candidate and former President Donald Trump reacts as multiple shots ring out during a campaign rally at the Butler Farm Show in Butler, Pennsylvania, July 13, 2024. (REUTERS/Brendan McDermid)

Comperatore, a former firefighter, shielded his wife and two daughters when gunshots were heard, Pennsylvania Gov. Josh Shapiro said. 

Crooks was fatally shot by U.S. Secret Service agents moments after opening fire. Authorities said he shot from an elevated position outside the security perimeter of the rally.

BIDEN SPOKE WITH TRUMP FOLLOWING SHOOTING AT PENNSYLVANIA RALLY

Undated file photo of Thomas Matthew Crooks

Undated file photo of Thomas Matthew Crooks. Crooks is alleged to be the shooter in the assassination attempt on former President Donald Trump in Butler, Pennsylvania on Saturday, July 13, 2024. (Fox News Digital law enforcement source)

Rallygoers said they noticed someone climbing to the roof of a nearby building and warned local police. 

The officer retreated down the ladder, and Crooks quickly took a shot toward Trump, according to The Associated Press. 

The first time Secret Service agents saw the gunman, he was already on the roof firing, Secret Service spokesperson Anthony Gugliemi told Fox News. 

Moments later, "a Secret Service Counter Sniper neutralized him," Gugliemi said. 

The FBI collected the weapon used in the shooting, an AR-Style rifle, and Crooks' cellphone. They are working to gain access to the device, the FBI said Sunday. 

Authorities believe the rifle used by Crooks was purchased legally by his father several months ago. It was still not clear how Crooks gained access to the weapon, the FBI said. 

An explosive device was found in the shooter's car, which was taken to the FBI in Quantico, Virginia, authorities said. Bomb-making materials were also found inside Crooks' home. 

Investigators are trying to determine a motive for the shooting. Crooks was a registered Republican, according to voting records, but he only participated in the Nov. 8, 2022, state election, due to his age. 

Records show that he made a $15 donation to Progressive Turnout Project, a Chicago-based political action committee that supports Democrat candidates for public office and claims to advocate for "key Democratic constituencies: young people, minorities and low-income people."

President Biden is expected to deliver an address from the Oval Office at 8 p.m. ET. On Saturday, he said he spoke with Trump and directed the Secret Service to provide Trump with "every resource capability and protective measure necessary to ensure his continued safety."

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On Sunday, the Secret Service said no changes were being made to the security plan for the Republican National Convention