U.S. Secret Service (USSS) leaders are holding a 1 p.m. update on the agency's internal investigation following the July 13 assassination attempt on former President Donald Trump at a campaign rally in Butler, Pennsylvania.

Acting Director Ronald Rowe said the agency had confirmed "communication deficiencies" that slowed its response when the gunman climbed up on a rooftop just outside the secure perimeter.

"For example, the Secret Service did not co-locate its security room with local law enforcement," he said. "There was an over-reliance on mobile devices, resulting in information being siloed."

He shared a timeline of events that showed communications were split between radio and phone, resulting in a delayed response to the initial alert that something was going on at the AGR building, within 150 yards of the former president. 

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Acting U.S. Secret Service Director Ronald Rowe Jr. testifies before a joint hearing of the Senate Judiciary and Homeland Security and Government Affairs committees on Capitol Hill on July 30, 2024 in Washington, D.C. (Michael A. McCoy for The Washington Post via Getty Images)

"At approximately 1810 local time, by a phone call, the Secret Service security room calls the counter sniper response agent, reporting an individual on the roof of the building," Rowe said. "That vital piece of information was not relayed over the Secret Service Radio network."

US Secret Service's July 13 Timeline:

• 18:10:00 - USSS informed over radio that local police were addressing an issue at "3 o'clock" on outer perimeter; USSS security room calls counter sniper
• 18:10:54 - Local police bodycam shows officers confront gunman Thomas Crooks on top of the AGR building
• 18:11:05 Site special agent calls assistant site special agent on phone to find out what's going on
• 18:11:32 - Bodycam video shows the first volley of shots fired
• 18:11:36 - Bodycam records a second volley of shots fired
• 18:11:47 - Bodycam footage shows the Secret Service counter sniper return fire and neutralize the shooter

Local police, through their own separate radios, were alerted to Crooks roughly two minutes earlier.

When asked directly about who was responsible for security on the rooftop, Rowe said the Service hadn't given adequate guidance to local assets.

"There should have been clearer direction about what we needed done at the AGR building," he said.

In the aftermath of the shooting, former Secret Service Director Kimberly Cheatle resigned, and at least five people were placed on administrative duty as the investigation unfolded. Separate investigations are underway by the House and FBI.

Police snipers return fire after shots were fired while Republican presidential candidate former President Donald Trump was speaking at a campaign event in Butler, Pa., on Saturday, July 13, 2024. SWAT expert Gene Petrino pointed out that snipers who shot Crooks were on a sloped roof, despite Secret Service Director Kimberly Cheatle's claim that they weren't stationed on the roof of the building Crooks climbed because of the "safety concern" a sloped roof posed. (AP Photo/Gene J. Puskar)

Rowe described the Secret Service's preparation for the rally, during which gunman Thomas Matthew Crooks, 20, killed one spectator and injured two others while striking Trump in the ear, as "a failure."

The suspect had a clear line of sight of the former president from an unprotected rooftop about 150 yards away.

"In today’s hyperdynamic threat environment, the mission of the Secret Service is clear: we cannot afford to fail," Rowe said.

As a result of these failures, what has become clear to me is we need a shift in paradigm in how we conduct our operations. As was demonstrated on Sunday in West Palm Beach, the threat level is evolving and requires this paradigm shift.

— Ronald Rowe, acting director of the U.S. Secret Service

Former President Donald Trump speaks at a rally in Uniondale, New York, on Wednesday, Sept. 18, 2024. Trump praised his Secret Service detail as "outstanding" during his remarks, which came just days after a second thwarted attempt on his life. (Julia Bonavita/Fox News Digital )

"It’s important that we hold ourselves to account for the failures of July 13 and that we use the lessons learned to make sure that we do not have another mission failure like this again," Rowe said. 

He said the agency is moving into "the accountability phase" – and actions are expected against officials who failed to secure the site.

Republican presidential candidate former President Donald Trump is rushed offstage during a rally on July 13, 2024 in Butler, Pennsylvania. Butler County district attorney Richard Goldinger said the shooter is dead after injuring former U.S. President Donald Trump, killing one audience member and injuring another in the shooting.  (Anna Moneymaker/Getty Images)

Rowe declined to go into specifics about how many people would be disciplined or at what level of senior, but he disputed prior reporting that he had asked anyone to retire already.

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"The Office of Professional Responsibility and the Office of Integrity are reviewing the findings," Rowe said. "This agency has among the most robust table of penalties in the federal government, and violations of policy will result in disciplinary action."

Thomas Matthew Crooks crawling on a roof moments before he attempted to assassinate former President Donald Trump. (DJ Laughery)

On Sunday, USSS thwarted a second assassination attempt, according to authorities.

An agent on Trump's protective detail was walking a few hundred yards ahead of him at the Trump International Golf Club in West Palm Beach, Florida, when they saw a rifle barrel poking out of the tree line along the perimeter.

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Ryan W. Routh, suspected of attempting to assassinate former President Donald Trump at his West Palm Beach golf course, stands handcuffed after his arrest during a traffic stop near Palm City, Florida, on Sept. 15, 2024. (Martin County Sheriff's Office/Handout via REUTERS)

Trump praised the agent who opened fire and caused the suspect to drop the gun and flee.

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Deputies later arrested a man named Ryan Routh, who they say camped out next to the fence for nearly 12 hours with a loaded SKS, a digital video camera, food and other supplies before the agent spotted him.