"What I saw made me ashamed," Secret Service head says of Trump rally security

• The shooter, later identified as Thomas Matthew Crooks, fired shots from the roof of a building owned by AGR International, a manufacturing company in Pennsylvania.

What they're saying: "Based on what I know right now, neither the Secret Service counter sniper teams nor members of the former president's security detail had any knowledge that there was a man on the AGR roof with a firearm," Rowe said at a joint congressional hearing.

• He said personnel were not aware "the assailant had a firearm until they heard gunshots."
• During questioning, he told lawmakers information was "stuck" or "siloed" in a local security channel, adding, "Nothing about man on the roof, nothing about man with a gun ... made it over our net."
• Rowe said that within 15.5 seconds after Crooks fired the first of eight shots, he was "neutralized."

Zoom in: Rowe said he traveled to the Butler rally site shortly after becoming acting director and laid on the roof Crooks positioned himself on.

• "What I saw made me ashamed," he said, adding, "I cannot defend why that roof was not better secured."
• He said during questioning that there was a "connectivity challenge" that hindered a counter-drone system being deployed earlier in the day that could have detected Crooks' use of a drone.
• "I feel as though we could have perhaps found him," he said. "We could have maybe stopped him."

Between the lines: Rowe outlined swift changes he's made at the the agency and struck a different tone than former director Kimberly Cheatle did during her grilling on Capitol Hill.

• Cheatle resigned after mounting bipartisan calls for her to step away or be fired.
• Rowe pledged "full support" to ongoing investigations and said he takes calls for accountability "very seriously," adding the Secret Service Office of Professional Responsibility is "reviewing the actions and decision-making" before and on the day of the attack.
• At the conclusion of the hearing, Rowe agreed to commit to having agents available for congressional interviews in a matter of days.

Sen. Rand Paul (R-KY.) addressed Rowe after he delivered an emotional answer and presented recreated images depicting the view of Crooks' prone position on the roof.

• "Director, I'm encouraged by your attitude, what you brought here today," Paul said.

Yes, but: Later in the hearing, shouting erupted between Republican lawmakers and Rowe.

• Sen. Josh Hawley (R-MO.) repeatedly questioned why no one had been fired over the security failures that day, to which Rowe said he would not rush to judgment amid ongoing investigations.
• "This could have been our Texas School Book Depository," the Secret Service chief said during the back-and-forth with Hawley. "I have lost sleep over that for the last 17 days."

FBI Deputy Director Paul Abbate, who testified alongside Rowe, revealed that the agency uncovered a social media account believed to be associated with Crooks that espoused antisemitic and anti-immigrant rhetoric.

• He provided a timeline from the FBI investigation, saying the US Secret Service command post was notified of a suspicious person roughly 25 minutes before the shooting.

Go deeper: Secret Service protocols scrutinized following Trump assassination attempt

Editor's note: This story has been updated with the latest details.