A US Secret Service probe has found communication gaps and a lack of diligence ahead of the attempted assassination of Republican presidential candidate Donald Trump at a Pennsylvania rally in July.

“There was complacency on the part of” some agents “that led to a breach of security protocols”, Acting Secret Service Director Ronald Rowe told reporters on Friday, adding that agency employees will be held accountable.

The review “identified deficiencies in the advanced planning and its implementation by Secret Service personnel”, he added.

Among the failures identified by Rowe was poor communication with local law enforcement; an “over-reliance” on mobile devices “resulting in information being siloed” and line of sight issues, which “were acknowledged but not properly mitigated”.

“At approximately 18:10 local time, by a phone call, the Secret Service security room calls the countersniper response agent reporting an individual on the roof of the AGR building,” Rowe said. “That vital piece of information was not relayed over the Secret Service radio network.”

The assassination attempt against Trump at the July 13 rally led to widespread criticism of the Secret Service and the resignation of its former director. Critics raised concerns about how the suspect was able to access a nearby rooftop with a direct line of sight to where the former president was speaking.

Trump’s ear was wounded, a rally attendee was killed and two others were wounded in the shooting. The Secret Service has since said it was “ashamed” of the security lapse.

Authorities are also probing a separate apparent assassination attempt against Trump in Florida on Sunday. In that case, the Secret Service caught the suspect and no shots were fired at Trump.

Rowe said that Trump was getting the same level of protection as President Joe Biden and Democratic presidential candidate Vice President Kamala Harris, his rival in the November 5 election.