WASHINGTON (Reuters) - The man who breached security at the White House this month overpowered a U.S. Secret Service officer and ran through much of the main floor, penetrating farther into the building than previously disclosed, the Washington Post reported on Monday, citing three people familiar with the incident.

A Secret Service official who spoke on condition of anonymity said an alarm box near the front entrance of the White House had been muted, the Post said.

“The Secret Service has no comment on that at this time due to the ongoing investigation,” Brian Leary, a spokesman for the agency, said of the Post story. A White House spokesman declined comment.

The suspect, Omar Gonzalez, 42, was charged with unlawfully entering a restricted building or grounds while carrying a deadly or dangerous weapon. Officials said he was carrying a knife when he jumped the White House fence and entered the executive mansion on Sept. 19.

A prosecutor said in court last week that officers found more than 800 rounds of ammunition, two hatchets and a machete in Gonzalez' car.

Gonzalez, a decorated Iraq war veteran, had been arrested in July with a sniper rifle and a map on which the executive mansion was marked, the prosecutor said.

The Post said Gonzalez ran past a guard immediately inside the door, past the stairway leading up to the Obama family's living quarters and into the East Room, where he was tackled at the far end of the room by an agent.

The alarm box near the entrance, designed to alert guards to an intruder, had been muted at what officers believe was the request of the usher's office, the Post said, citing the Secret Service official.

The officer posted inside the door appeared to be delayed in learning the intruder was about to come through, the Post said. Officers are trained to lock the front door immediately if they learn of an intruder on the grounds.

Secret Service Director Julia Pierson is expected to face questioning at a congressional committee hearing on Tuesday.

(Writing by Jim Loney; Editing by Peter Cooney)