Lack of training, poor staffing decisions and communication problems contributed to the ability of an armed White House intruder to climb over a security fence and run into the executive mansion earlier this year, according to a Homeland Security Department review of the incident.

Investigators found that the first alerts about Omar Gonzalez making it over the White House fence on Sept. 19 were brief, at times “unclear and muffled,” and never reached key posts inside the White House because emergency communications receivers were muted.

At one point, Gonzalez raced through heavy brush inside the White House grounds to elude pursuing agents. “Officers were surprised that Gonzalez was able to get through the bushes; prior to that evening, officers believed the bushes too thick to be passable,” the report said.

A nine-page summary of the department’s review said Secret Service officers on duty that night didn’t even see Gonzalez climb a White House fence because their view of the grounds was blocked by a construction project.

Other officers saw Gonzalez start to climb the barrier, ordering him to stop, but weren’t able to reach him before the Army veteran carrying a small knife made it on to the White House lawn and start running toward the building.

He was eventually subdued deep inside the White House after running into the building through an unlocked door.

The deputy Homeland Security secretary, Alejandro Mayorkas, led the internal review of the incident. The White House breach and details of previously unknown presidential security problems ultimately led to the resignation of former Secret Service Director Julia Pierson.

(AP)