A law enforcement officer reportedly "retreated" from a chance to stop a gunman before former President Donald Trump was shot in the ear over the weekend.

In a report on Sunday, The Associated Press provided new details about the seconds leading up to Trump's attempted assassination.

Moments before a man who the FBI identified as 20-year-old Thomas Matthew Crooks fired shots toward Trump's rally, a local law enforcement officer was said to have backed down from a confrontation with the suspect.

"One local police officer climbed to the roof and encountered Crooks, who pointed his rifle at the officer," the AP report said. "The officer retreated down the ladder, and Crooks quickly took a shot toward Trump, and that's when Secret Service snipers shot him, said the officials, who spoke to The Associated Press on condition of anonymity to discuss an ongoing investigation."

The report also noted that rallygoers warned police about a man climbing a ladder to the top of a building near the event in Butler, Pennsylvania.

Although Trump survived the shooting, at least one person was killed by the gunman, who was shot to death by Secret Service agents.

Authorities told AP that Crooks used an AR-style rifle, which was recovered at the scene. Explosives were also said to be found in the gunman's vehicle and home.