(NewsNation) — The acting director of the Secret Service called the security response surrounding the assassination attempt against former President Donald Trump a “failure on multiple levels” at a Senate committee hearing Tuesday, saying he was “ashamed” of it.

Ronald Rowe and FBI Deputy Director Paul Abbate are appearing before a joint hearing of the Senate Judiciary and Homeland Security committees. The Secret Service was responsible for protecting Trump at the July 13 rally in Butler, Pennsylvania, when the shooting occurred, while the FBI is leading the investigation into what went wrong.

“I went to the roof of the AGR building where the assailant fired shots and I laid a prone position to evaluate his line of sight. What I saw made me ashamed,” Rowe said. “As a career law enforcement officer and a 25-year veteran with the Secret Service, I cannot defend why that roof was not better secured.”

To prevent future lapses, Rowe said the Secret Service has expanded its use of drones at protective sites to detect threats on roofs and other elevated locations. Later, Rowe testified that the Secret Service’s late deployment of counter-drone operations at the rally is “something that has cost me a lot of sleep.” Connectivity issues had caused the delay, Rowe said. It has previously been reported that the shooter used a drone near the site of the rally in the hours before it started.

Other measures Rowe has taken is directing Secret Service personnel to ensure every site security plan is thoroughly vetted by multiple experienced supervisors.

“It is clear to me that other protective enhancements could have strengthened our security at the Butler event,” Rowe said. 

While Rowe acknowledged his own agency’s mistakes, he also criticized local law enforcement for not sharing that the gunman was spotted on a roof near the rally site more than 90 minutes prior to the shooting.

“It is troubling to me that we did not get that information as quickly as we should have,” Rowe said. “We didn’t know that there was this incident going on.”

A motive for the shooting has not been identified by authorities. On Tuesday, Abbate told lawmakers the FBI believes a social media account tied to the shooter posted multiple antisemitic and anti-immigrant messages and comments, while other posts seemed to espouse political violence.

Many false conspiracy theories have spread following the attempt on Trump’s life. Rowe debunked one in his opening comments to the committee, saying the Secret Service sniper who shot and killed the gunman was not denied permission to take him out.

Secret Service snipers always have the green light to take out a threat and don’t need additional permission, Rowe clarified.

FBI deputy director’s timeline of Trump assassination attempt

Abbate laid out a timeline of the moments before the gunman opened fire — one of the clearest ones yet. 

Law enforcement, Abbate said first flagged the shooter, Thomas Matthew Crooks, 20, at approximately 4:26 p.m. and he was identified as a suspicious person at 5:14 p.m.

At 5:32 p.m., a local SWAT operator took a photo of the shooter. The Secret Service command post was notified about Crooks being identified as a suspicious person 25 minutes before the shooting. 

From about 6:02 p.m. to 6:08 p.m, law enforcement officers lost sight of the Crooks. He was observed on the roof by local law enforcement at 6:08 p.m., Abbate said.  

Around 6:11 p.m. a local police officer was lifted to the roof by another officer, saw Crooks and radioed that he was armed with “a long gun,” Abbate said.

Within approximately the next 30 seconds, the shots were fired.

Why previous USSS director stepped down

The hearing comes on the heels of the disastrous appearance last week by former Secret Service Director Kimberly Cheatle before the House Oversight and Accountability Committee, where she frustrated lawmakers, including Chair James Comer, R-Ky., and Maryland Rep. Jamie Raskin, the panel’s top Democrat, for failing “to provide answers to basic questions regarding that stunning operational failure.”

Republican lawmakers called on others to lose their jobs because of the shooting. Sen. Lindsey Graham, R-S.C., said f something like this happened in the military, “a lot of people would be fired.”

“And if a lot of people are not fired, the system failed yet again,” Graham added.

She resigned the following day.

FBI Director Christopher Wray was more forthcoming when he appeared before the House Judiciary Committee last week, but legislators still want more information from Rowe, who briefed senators last week ahead of Tuesday’s joint hearing. 

The Associated Press contributed to this report.