Shots fired at the Pentagon, police say

[Lex]

Washington (CNN) -- Shots were fired at the Pentagon early Tuesday, authorities said, striking a window of the building.

Pentagon police spokesman Chris Layman said it's not known who fired the shots. Pentagon police officers heard at least five shots around 4:50 a.m., Layman added.

According to another Pentagon Force Protection Agency spokesman, Terry Sutherland, two bullets hit the Pentagon on the south side of the building -- one striking a window and the other hitting the building itself. This is an unoccupied part of the building that is being renovated.

Sutherland said a fragment of one of the bullets is lodged in the window. The windows, which are bullet-proof, did not shatter.

There was a partial lockdown of the Pentagon's south parking lot and south entrance for about an hour after the shooting, and authorities briefly shut down a portion of Interstate 395 going out of the capital -- which runs along the south side of the Pentagon -- to conduct a search in the investigation.

Maj. Chris Perrine, a public affairs officer for Defense Press Operations, said other temporary road closures may be necessary as police conduct their investigation.

Officials will hold a news conference about the incident at 11:30 a.m. at the Pentagon.

Tuesday's shooting follows a similar incident Sunday at the National Museum of the Marine Corps in Triangle, Virginia, near the entrance of Marine Corps Base Quantico. A police statement Monday said "an unknown shooter or shooters fired shots at the National Museum of the Marine Corps, causing minor damage to the building's windowed roof and a steel wall at the base of the structure.

"The museum was unoccupied at the time of the incident, and no one was injured," the statement said.

Military police and the Prince William County Police Department are investigating that incident.

CNN, October 19, 2010 11:21 a.m. EDT