Thomas Matthew Cooks was planted on the roof of a manufacturing plant located over 130 yards away from the stage at Butler Farm Show grounds, the New York Post reported, citing sources.
Authorities used the gun to help determine the shooter's identity, as he did not have identification on him, according to law enforcement sources, as reported by CNN.
He lived in the Pittsburgh suburb of Bethel Park, about 56 km south of the Trump rally site where law enforcement officials said he fired at Trump, the presumptive presidential candidate of the Republican Party.
The shooter, as per FBI, used an AR-style rifle chambered in 5.56mm, a common calibre for such weapons.
Two witnesses at Donald Trump's election rally in Pennsylvania, where he was attacked, claimed to have seen the shooter, with one recalling how the gunman moved from roof to roof, apparently scouting for a perfect perch to shoot at the former US president.
Reacting to the FBI's statement, Trump told his supporters that he has accepted an apology from the FBI.
Trump also said he appreciated the call he received from President Joe Biden, also expected to be his rival in the election, according to the Post, calling it "fine" and "very nice."
Former United States president Donald Trump was injured after being shot in the ear during an apparent assassination attempt at an election rally in Pennsylvania after which a male attacker was shot and killed by a member of the Secret Service.
Opener Dawid Malan hit a superb century before Moeen Ali grabbed four wickets as England beat New Zealand by 100 runs in the fourth One-Day International on Friday for a 3-1 series victory.
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The 92nd Academy Awards nominations have been announced at the Samuel Goldwyn Theatre in Beverly Hills, Los Angeles.
The 92nd Annual Academy Awards hardly had any surprises up its sleeves. Here's a quick look at the winners.
On a roll after five wins on the trot, table toppers Mumbai Indians will look to continue their domination when they clash with struggling Delhi Daredevils in an Indian Premier League game, in Mumbai, on Saturday.
Drafted into the team for the first time in the ongoing cricket World Cup, Pakistan wicketkeeper Sarfraz Ahmed made an instant impact with a record-equalling six catches and 49 runs in the team's upset win over South Africa in Auckland.
Ben Stokes smashed an unbeaten century as England outclassed World champions Australia by 40 runs via the Duckworth-Lewis method in a rain-hit match to knock them out of the ICC Champions Trophy, in Birmingham, on Saturday.
Barring Sri Lanka's Kumar Sangakkara, all players have declared their allegiances to IPL franchises over their respective countries' domestic sides ahead of the upcoming Champions League Twenty20.