There were at least six safeguards that failed when a man jumped the fence and got deeper into the White House, according to reports.
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Secret Service Director Julia Pierson appeared today before a House Committee over the biggest breach in security since she took over the post in March last year.
"I take full responsibility. It will never happen again," Pierson said at the beginning of the hearing without elaborating.
Though the agency's spokesperson initially said that former veteran Omar Gonzalez was apprehended just inside the North Portico doors during the September 19 incident, authorities have now said that to be false.
Further details first reported by The Washington Post indicate that there were a half dozen steps that were not taken by the Secret Service during the close call, just minutes after the Obamas had left the building.
"How on earth did it happen?" Chairman on Oversight and Government Reform Congressman Darrell Issa said in his opening statements at Pierson's hearing this morning.
"The fact is the system broke down on September 19," Issa added.
Here's a step-by-step look at what happened, according to three sources quoted by The Washington Post:
The Fence and Plainclothes Officers
The first breach that occurred came when a team of plainclothes Secret Service agents circulating the perimeter of the white House fence did not spot Gonzalez as he climbed over. That team is in place as an early warning intended to alert the rest of the Secret Service team.
Crash Boxes and Front Door
When any officer spots an intruder -- which should have been the plainclothes team -- agents should hit the red button in the "crash boxes" posted throughout the White House and grounds. That alarm would lock the door to the White House, but since the never went off, the doors were left unlocked.
The plainsclothes agent failed to spot someone climbing the fence, there is an officer stationed in a guard booth on the North Lawn, The Washington Post reported.
If that officer sees the intruder, but realizes that they will not be able to apprehend them before they reach the White House, the officer is supposed to send an attack dog to stop the intruder.
According to The Washington Post, people familiar with the incident said that the officer may not have felt that they could release the attack dog because there were other Secret Service officers pursuing Gonzalez by foot, and the officer may have feared that the dog would attack the Secret Service agents rather than the intruder.
SWAT Team and Extra Guard
The guard in the North Lawn booth is also trained to send a SWAT team and a guard to the front door to confront the intruder. Neither of these were sent.
Guard at the Front Desk
The final breach came when Gonzalez ran past the guard inside the North Portico door, through the entrance hallway, down a hall past the staircase that would lead him directly to the First Family's private residence and into the East Room. It was only there, in the room used for formal state dinners and national security announcements, where Gonzalez was finally taken and physically tackled by an off-duty agent who was leaving for the day, the newspaper reported today.