The Secret Service said on Thursday that it was suspending six agents involved in securing the site of a campaign rally where a gunman tried to assassinate Donald J. Trump last summer.

The suspensions range from 10 to 42 days, without pay, the agency said in a statement that came days before the first anniversary of the shooting. It did not give timing for the suspensions or name the agents, citing privacy law. All six had been placed on restricted duty after the shooting while the agency conducted its internal review.

A young junior agent who was on Mr. Trump’s personal detail at the time received the longest suspension, according to a person familiar with the situation who was not authorized to discuss personnel matters. That agent is also the only member of Mr. Trump’s personal detail to receive a suspension, the person said.

The agency has come under intense scrutiny since a 20-year-old gunman was able to fire several shots at Mr. Trump as he spoke onstage at a campaign rally on July 13, 2024, in Butler, Pa. It was the first assassination attempt since 1981 to wound a current or former president — a bullet grazed Mr. Trump’s ear. A volunteer firefighter in the crowd, Corey Comperatore, was killed and two other attendees were injured. The gunman was killed by the Secret Service.

The agency’s director at the time, Kimberly A. Cheatle, resigned shortly afterward.

Lawmakers have called for agency leaders to hold those responsible accountable for operational failures. There was a second attempt on Mr. Trump’s life later the same year in September, as he golfed in Florida. Agents shot at the suspect who was hiding near the outer edge of the course.

In a statement on Thursday, the agency’s director, Sean M. Curran, reflected on the events in Butler. At the time, Mr. Curran was the lead agent on Mr. Trump’s personal security detail and was one of the agents who lunged to Mr. Trump’s side to shelter him after shots were fired. In January, Mr. Trump promoted him to lead the agency.