The sniper hit Trump’s gunman’s weapon and slowed him down.

A police sniper may have saved lives by shooting at the rifle of Donald Trump’s would-be assassin and taking him down, an investigation has found.

The sniper’s bullet damaged Thomas Matthew Crooks’ gun and interrupted his aim after he fired his first shot in Butler, Pennsylvania, according to Louisiana Rep. Clay Higgins. A Secret Service sniper killed him minutes later.

The report comes as the Secret Service temporarily transferred some bodyguards from President Joe Biden to Trump, according to US media.

Trump will also be equipped with bulletproof glass so he can continue his outdoor campaign rallies.

The former president was unprotected at a July 13 rally in Butler when a bullet nearly hit him in the head.

Mr Higgins’ report said a Butler SWAT officer was the first to fire on Trump’s assassin — from about 100 yards away.

The sniper “ran towards the threat, ran into a clear firing position right in the line of fire,” the congressman said.

Then, with just one shot, he shot the gunman and partially nicked his rifle, the report said.

The move caused the gunman to temporarily lose his position, but “after just a few seconds” he “swam back” before being shot dead by a Secret Service gunman.

The attackers killed one person in the crowd and seriously injured two others.

Security around the former president has been stepped up since then.

New record achieved by ABC News The files detail internal discussions among local authorities about planned security on the day of the shooting, with the Butler County sheriff noting the “circus” and large crowds the rally would bring. The files also include text messages that show frustration among local authorities following the shooting.

Local authorities have discussed with the Secret Service requesting sniper and surveillance support, along with counter-assault teams and rapid reaction forces.

In an email obtained by ABC News to the Butler County prosecutor, Adams Township Police Department Sergeant Edward Lenz detailed that they plan to provide two snipers, a rapid reaction force and two mobile counterattack teams.

Counterattack teams, he wrote, “will respond to and address an attack on a presidential candidate inside the venue, whether it is a coordinated attack by multiple attackers or a lone attacker.”

He said a rapid response force would respond to any “high-risk incidents occurring outside the venue”.

The filing comes after Secret Service agents were deployed amid threats against Trump, 78. According to a report in The New York Times, the move was made because Mr Biden’s travel schedule was cut back after he dropped out of the race.

A source told the newspaper that the officers deployed were responsible for accompanying Mr Biden or going ahead of him to set up security measures at an event.

Kimberly Cheatle, director of the Secret Service, resigned on July 23 after the US House of Representatives hearing on the assassination.

Politicians on the House Oversight Committee criticized her lack of information about security plans and how police responded to reports of suspicious behavior by the gunman before the shooting.

The gunman, 20-year-old Thomas Matthew Crooks, was shot dead by a Secret Service sniper team after he fired eight bullets at Mr Trump from a rooftop just outside the secure area of ​​the rally.

The FBI is currently investigating this security flaw and political leaders in the US Congress have also begun investigating.