At least five Secret Service agents have been placed on modified duty after the assassination attempt on former President Donald Trump in July, a law enforcement official told The Associated Press.

They include the special agent in charge of the Pittsburgh field office and three other agents assigned to that office, which was responsible for the security planning ahead of the July 13 rally in Butler, Pennsylvania, according to the law enforcement official who had direct knowledge of the matter. One of the five agents was assigned to Trump's protective detail, the official said.

The official was not authorized to publicly disclose details of the personnel investigation and spoke to The Associated Press on condition of anonymity.

The agents are on administrative leave, meaning they cannot do investigative or protective work.

Multiple investigations have been launched as officials probe a complicated law enforcement failure that allowed a man with an AR-style rifle to get close enough to shoot and injure Trump at the rally.

Trump was struck in the ear but avoided serious injury. One spectator was killed and two others were injured.

The shooting was a devastating failure of one of the agency's core duties and led to the resignation of the Secret Service's then-director, Kim Cheatle.

At a congressional hearing after the assassination attempt, Cheatle acknowledged that the Secret Service was told about a suspicious person two to five times before the shooting. She also revealed that the roof from which Thomas Matthew Crooks opened fire had been identified as a potential vulnerability days before the rally.

Acting Secret Service Director Ronald Rowe Jr., who took over after Cheatle's resignation, has said he "cannot defend why that roof was not better secured."

__

Associated Press writer Rebecca Santana contributed to this report.