At least two shots fired by an unknown gunman or gunmen struck the Pentagon early Tuesday morning, Pentagon officials told NBC News.
According to the officials, the shots were fired at approximately 4:55 a.m. on the south side of the building. A Pentagon police officer heard a series of at least five potential shots fired in or near the south parking area of the Pentagon.
Pentagon Police locked down the south parking lot and the entrances to the building, but an initial sweep didn't find anything. Until about 5:40 a.m., it was impossible to enter or exit the building or the property known as the Pentagon reservation.
"We did take prompt action, immediately closing down the reservation -- vehicular access as well as access to the building -- pretty quickly when the report of shots fired was verified," said Steven Calvery, director of the civilian Pentagon Force Protection Agency, which is leading the investigation.MORE: click the Title link