The same gun was used in two of three recent shootings targeting military buildings in and near Washington, including the Pentagon, reports CNN's Pentagon correspondent Chris Lawrence.

Last week, shots were fired at the Pentagon, just two days after shots were fired at the National Museum of the Marine Corps in Virginia. Ballistics tests revealed both shootings involved a single weapon, the FBI said.

Authorities are investigating shots fired Monday night or early morning Tuesday at the Marine Corps recruiting station in Chantilly, Virginia.