Shots fired at the Pentagon, police say

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.  (Continues here at CNN)