Trump shooting updates: Shooter flew drone near site hours before shooting

House Speaker Mike Johnson recounted to ABC News on Tuesday what he told then-Secret Service Director Kim Cheatle when they met one-on-one on Monday.

"I made it clear, as I always do to anyone in these positions, 'This is not personal, ma'am,'" Johnson recalled. "'But you're No. 1 responsibility is performance -- and you did not perform. In fact, it was an utter failure, and we almost lost a former president because of it. And accountability begins at the top and you need to take responsibility.'"

Pennsylvania Gov. Josh Shapiro said Tuesday that Cheatle’s resignation was "the right thing to do."

"I mean, there were obviously incredible failures at the farm show in Butler. There are many investigations going on, and those investigations need to unearth what those failures were, so that any protectee is ensured the absolute top level of protection going forward. That was a failure in Butler. Thank God the former president was not assassinated," Shapiro said.

-ABC News’ Jay O’Brien and Will McDuffie

During a walk-through on July 11, the Pennsylvania State Police was told by the Secret Service that the Butler County Emergency Services Unit was responsible for security of the AGR building, where the shooter fired from during the July 13 rally, according to state police Col. Christopher Paris.

Paris told the House Homeland Security Committee on Tuesday that two Butler County ESU members were on the second floor of the building and positioned in the window.

Crooks was "initially spotted" from a second-story window and identified as a suspicious person, which prompted then ESU officers to leave their post and go search for the suspicious person, along with other officers, Paris said.

Paris said the gunman, Thomas Matthew Crooks, never made it to the safety perimeter itself.

"He was identified by those members as suspicious, in part because of that, and then at some point, he produced the rangefinder, which heightened that suspicion," Paris testified.

Police realized "very early on" that Crooks had a detonation device on his person, Paris said. It was a "serious tactical consideration" that Crooks could have blown up his vehicle and escaped from the scene, Paris said, but noted that because he was dead, there was no way to know.

-ABC News’ Luke Barr and Mike Levine

Secretary of Homeland Security Alejandro Mayorkas said he’s appointed Secret Service Deputy Director Ron Rowe to serve as acting director of the agency.

"A 24-year veteran of the Secret Service, he previously served as the agency’s Assistant Director for the Office of Intergovernmental and Legislative Affairs, Deputy Assistant Director for the Office of Protective Operations, and in other leadership positions," Mayorkas said in a statement. "I appreciate his willingness to lead the Secret Service at this incredibly challenging moment, as the agency works to get to the bottom of exactly what happened on July 13 and cooperate with ongoing investigations and Congressional oversight."

The Pennsylvania State Police has interviewed 100 people and gathered 1,000 pieces of evidence in the investigation into the homicide of Corey Comperatore and the two others injured in the shooting, Pennsylvania State Police Col. Christopher Paris told the House Homeland Security Committee on Tuesday. The state police is also investigating the U.S. Secret Service counter sniper who shot the gunman as an officer-involved shooting.

Paris said the state police had two main responsibilities: to assist the Secret Service with the motorcade and staff security posts within the secure perimeter.

The state police had 32 troopers staffed for the July 13 rally, he said.

Paris said the Secret Service notified the state police about the rally on July 5.

An initial planning meeting with law enforcement agencies was held on July 8. State police participated in a walk-through at the Butler Farm Show Grounds on July 11.

The state police said it provided all resources requested by the Secret Service.

-ABC News’ Luke Barr and Mike Levine