The FBI is investigating a vexing question: What is motivating someone to shoot at US military buildings in Washington, D.C.? As many as seven shots from what now appears to be a high-velocity rifle were fired at the Pentagon on Oct. 19, shattering but not penetrating the windows there, reports the Christian Science Monitor. Two days earlier, a gunman targeted the National Museum of the Marine Corps in Triangle, Va. A ballistics investigation found that a single weapon was used in both incidents, and the FBI is looking into yet another attack this week on a Marine Corps recruiting station in Chantilly, Va. Those ballistics tests aren't back yet.
Whether that person is a disgruntled former US marine or a would-be terrorist remains unknown, and Pentagon spokesman aren't speculating. Officials note, however, that all three shootings have occurred either overnight or early in the morning, when a shooter would likely not expect people to be around. No one has been injured in any of the shootings.