Someone fired shots at the Pentagon early Tuesday, hitting the building and causing minor damage, defense officials said.
Police who protect the massive Defense Department headquarters temporarily locked down some road and pedestrian entrances to the building after a civilian reported he may have heard shots at about 4:55 a.m. on the south side of the facility.
Two bullets, thought to have been fired from a rifle, struck but failed to penetrate the reinforced glass on one of the upper floor windows, NBC News reported. Work crews were in the process of removing the entire windows and frames as evidence.
NBC News reported that five shots had been heard.
A sweep of the area and facility found that some shots had hit the building, Marine Col. Dave Lapan, a Pentagon spokesman said. He didn't know how many or from what kind of weapon.
Roads and pedestrian entrances leading to the Pentagon were reopened a little after 5:30 a.m. but part of nearby Highway 395 was later temporarily closed for part of the investigation.
A dozen police also were seen at around 9 a.m. walking side-by-side in a line as they combed through a grassy area on the south side of the building.
Lapan said there were no injuries.
In response to a question, he said he did not know whether there was any connection between Tuesday's incident and Monday's discovery of bullet holes in windows at the National Museum of the Marine Corps in Triangle, Va., some 30 miles south of the Pentagon.
A cleaning crew at the museum associated with the Quantico Marine Base called police when they noticed the bullet holes in windows high up in a part of the building that faces Interstate 95.
Police believe the shots were fired at the museum late Saturday or early Sunday, when no one was inside. Investigators used a crane to inspect the damage Monday. Because of the height of the holes, police suspect the bullets were likely fired from a rifle, but they are still working to determine what caliber of bullet was used.
Several glass panels were hit, causing about $20,000 in damage. None of the museum's artifacts — including a Harrier jet hanging near the damaged windows — were hit.
Lapan said this was the first incident of its kind since March 4, when a gunman opened fire at a security checkpoint into the Pentagon in a point-blank attack that wounded two police officers.
The shooter, identified as John Patrick Bedell, 36, of Hollister, Calif., was shot by police and died hours after being admitted to a hospital in critical condition. Authorities had no motive for the shooting, but there had been signs that Bedell may have harbored resentment for the military and had doubts about the facts behind the Sept. 11 terrorist attacks.
Pentagon Force Protection Agency Director Steven Calvery said he was not aware that security at the Pentagon or any other military installation had been ratcheted up in response to the most recent incident, but he note there had already been an increase in police presence after the March shooting.