Courtesy Jerry Murphy, Associated Press
This Sept. 21, 2009 photo provided by Jerry Murphy shows Omar Gonzalez, who was married to Murphy's mother, Samantha, until they divorced in 2012. Authorities have identified Gonzalez as the man who got into the White House after scaling a fence on Friday, Sept. 19, 2014.

WASHINGTON — Investigators found more than 800 rounds of ammunition, a machete and two hatchets in the car of the former soldier accused of scaling the White House fence and sprinting inside the building while carrying a knife, a federal prosecutor said Monday. President Barack Obama said he was "obviously concerned" about the weekend incident.

The Secret Service increased security around the famous grounds on Pennsylvania Avenue in the nation's capital, some guards openly holding weapons, others escorting dogs. There was talk of expanding White House security beyond the current area as a major investigation began into the question of how the man managed to get to the building without being stopped.

Forty-two-year-old Omar J. Gonzalez of Copperas Cove, Texas, faces charges of entering a restricted building or grounds while carrying a deadly or dangerous weapon. He had been arrested earlier in the summer in Virginia with a carful of weapons, authorities said, and a federal prosecutor said Monday in court that Gonzalez had had a map with the White House circled.

Obama and his family had left the White House for Camp David when the incident occurred Friday evening. Gonzalez was seized just inside the building's front door. No guns were found in his car.

In court, Gonzalez, with a gray beard, a shaved head and dressed in a standard prison orange jumpsuit, listened impassively as the prosecutor spoke. He could face up to 10 years in prison if convicted of illegally entering a restricted area with a dangerous weapon.

The Army said he served from 1997 until his discharge in 2003, and again from 2005 to December 2012, when he retired due to disability.

Obama, asked about the incident at the White House, said, "The Secret Service does a great job, and I'm grateful for the sacrifices that they make on my behalf -- and my family's behalf."

But spokesman Josh Earnest said the president was "obviously concerned" about what had happened.

At the federal court hearing, Assistant U.S. Attorney David Mudd said Gonzalez already was under indictment in southwestern Virginia, accused of having a sawed-off shotgun and trying to elude police this summer.

Wythe County Deputy Commonwealth Attorney David Saliba said by telephone that Gonzales also had two powerful rifles, four handguns and other guns and ammunition in his Ford Bronco when troopers stopped him on July 19. The weapons and ammunition were seized, but Gonzalez was released on bail.

Earnest said the Secret Service investigation will include a review of protective efforts both inside the White House grounds and outside the fence line along Pennsylvania Avenue, including staffing and threat assessment policies and procedures.

The House Oversight and Government Reform Committee announced it would hold a hearing next week.

Homeland Security Secretary Jeh Johnson said he would ultimately review the findings of the investigation ordered by Secret Service Director Julia Pierson. Johnson said the public should not rush to judgment about the security breach and urged against second-guessing security officers whom he said "had only seconds to act."

The Secret Service didn't open fire on Gonzalez or send attack dogs after him.

Officers who spotted Gonzalez scale the fence quickly assessed that he didn't have any weapons in his hands and wasn't wearing clothing that could conceal substantial quantities of explosives, a primary reason agents did not fire their weapons, according to a U.S. official briefed on the investigation.

Another consideration was whether bystanders behind the fence could have been injured by errant gunfire, said the official, who was not authorized to discuss the investigation by name and spoke only on condition of anonymity.

The Secret Service has long tried to balance public access to the "People's House" and security of the presidential residence.

The two-block stretch of Pennsylvania Avenue in front of the White House's north gates has been closed to vehicle traffic since May 1995, when President Bill Clinton ordered the immediate closure of the road in an effort to prevent a potential car- or truck-bomb attack.

On any given day, numerous uniformed officers can be seen patrolling parts of the sprawling lawns on either side of the White House, and others are stationed along the fence line on Pennsylvania Avenue. Many more were in view on Monday.

But the pedestrian-only zone hasn't entirely prevented security breaches along the fence.

Last September a man was arrested and accused of throwing firecrackers over the fence on the north lawn, near the area where Gonzalez is accused of climbing over the barrier. The Secret Service at the time said the man with firecrackers did not pose a threat.

A few weeks later a Connecticut woman set off a police chase through downtown Washington after ramming a security checkpoint near the White House. Miriam Carey, 34, was shot and killed by police near the Capitol.

In May, a man was arrested after he followed a motorcade carrying President Obama's daughters through the gates into the secure area near the White House. He had a pass for the Treasury Department, which is next door and also inside the pedestrian-only security zone. A charge of unlawful entry was later dismissed.

On a lighter note, in August a toddler managed to slip through the slats in the metal fence. The Secret Service joked that they would wait until the boy learned to talk before questioning him.

Less than 24 hours after Gonzalez's arrest, a second man was taken into custody after he drove up to a White House gate and refused to leave, Secret Service spokesman Ed Donovan said. Bomb technicians in full gear searched the vehicle as agents briefly shut down nearby streets.

On Sunday, Secret Service spokesman Brian Leary identified the man as Kevin Carr, 19, of Shamong, New Jersey.

There was no indication the two incidents were connected. But they only intensified the scrutiny of the Secret Service, which is struggling to rehabilitate its image following a series of allegations of misconduct by agents in recent years, including agents on Obama's protective detail.

Associated Press writers Josh Lederman, Jessica Gresko and Julie Pace contributed to this report.