WASHINGTON (AP) — A string of security lapses resulted in a four-day delay before the U.S. Secret Service realized that a man had fired a high-powered rifle at the White House in 2011, an incident that could have put President Barack Obama’s daughters at risk, according to a Washington Post investigation.

At issue is what the Post calls the Secret Service’s bungled response to the case of Oscar R. Ortega-Hernandez, an Idaho man who was sentenced to 25 years in prison after firing at least seven bullets at the White House on November 11, 2011. The president and Michelle Obama were away, but their daughters were in Washington — one at home and the other due to return that night.

A White House usher expressed concerns about the safety of Malia Obama, who was to arrive within minutes of the reports of the shots, The Post reported. The usher told the staff to keep Sasha Obama and her grandmother, Marian Robinson, inside.

The reports of shots fired that night were not connected to the White House until four days later when a White House housekeeper noticed broken glass and a chunk of cement on the floor inside. Ortega, who fled the scene, was arrested the day after that.

The Post story alleges that some Secret Service officers knew immediately that shots had been fired into the White House, but that they were “largely ignored, and some were afraid to dispute their bosses’ conclusions” that the shooting was not directed at the White House. The service conducted only a cursory inspection of the White House for evidence or damage, the Post said, and key witnesses were not interviewed until after bullets were found.

The suspect was able to park his car on a public street, take several shots and then speed off without being detected, the Post noted, calling it “sheer luck” that Ortega was identified as the shooter, mainly because the troubled and jobless 21-year-old wrecked his car seven blocks away and left his gun inside.

The Post based its story on interviews with agents, investigators and other government officials and hundreds of pages of documents, including transcripts of interviews with officers on duty that night and audio recordings of radio transmissions.

In a statement to the Associated Press, the Secret Service said it “implemented both personnel and structural enhancements” following a review of the incident, “and other physical and technical enhancements, including additional surveillance cameras.”

A Secret Service official, who requested anonymity for lack of authorization to comment for attribution, said the delay in understanding what happened that night was not the result of misconduct or incompetence, but “an uncertain situation” that included echoing shots from a quarter mile away and confused initial witness reports.

“I’m not saying this was our shining moment, but we never stopped looking for this guy,” the official said.

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