A Secret Service police officer stands outside the White House in Washington, Monday, Sept. 22, 2014. (Evan Vucci/AP)

Deputy National Security Adviser Tony Blinken defended the Secret Service on Sunday after a Washington Post report that it took four days for the agency to realize in November 2011 that a gunman had hit the White House.

The Post reported on the Secret Service’s slow response to gunfire in 2011 this weekend.

“Their task is incredible, and the burden that they bear is incredible,” Blinken said Sunday on CNN’s “State of the Union.” “Director [Julia] Pierson has been looking at this incident. And then what we saw last week, she reported to the president on Thursday evening when he got back from New York. The Secret Service is investigating this and they will take any steps necessary to correct any deficiency.”

Earlier this month, a man jumped the White House fence and reached the unlocked front door. That and other recent lapses have led to increased scrutiny of those who protect the president.

After the fence-jumping incident, temporary metal barriers were set up.

The sectional fencing, which is marked by yellow “Police Line Do Not Cross” signs, created an additional buffer of about five feet between the public and the ornamental fence.

On Sunday, the plaza was calm as visitors leaned against the new barriers to view the White House and pose for pictures. Protesters, including some who have occupied Lafayette Square for years, were using microphones to address the public and passing out brochures.

“It’s intimidating,” said Ryan Powers, 20, a George Mason University student from Madison, Va. Powers said he would not object if the metal barriers were temporary while the Secret Service took other, less intrusive measures, but he said he was more uneasy about the idea that the barriers could become permanent.

“I think it’s amazing how fast they responded,” Powers said. “I think it does show that the U.S. does respond to domestic threats.”

Nancy Eade, 53, a receptionist who was visiting the nation’s capital from Green Bay, Wis., objected to the new barrier, saying it was an “eyesore” that — literally and symbolically — distances people from their leaders.

“I know it’s only two feet, but it’s two feet more,” Eade said, adding that she viewed the Secret Service response as a “knee-jerk reaction.”

“This particular block has to be the most protected in the nation. To give it a two-foot buffer, I don’t think it’s necessary,” she said.