The shooting incident apparently occurred between 9 p.m. and 6 a.m., just hours after the FBI linked Tuesday night's shooting at a Marine recruiting center in Chantilly, Va., with two similar cases in the commonwealth -- including an earlier incident at the museum.
Investigators believe the person shooting has some type of issue with the Marine Corps and they are working under the assumption that he is or was a member of the Marines.
"We'd like to know what his grievance is and how we can try to resolve it," said John Perren of the FBI. "We'd like to hear his side of the story."
They also said they don't believe the shooter is trying to hurt anyone because of the timing of the shootings.
"We understand he may feel a great deal of stress in his life at this moment," Perren said. "However, relieving his stress by shooting at buildings puts others at risk. Acting out this way can eventually lead to disastrous and tragic consequences that we all wish to avoid."
Officials said that the most recent shots hit the west side of the building and came from the direction of Interstate 95. They do not know the caliber of the bullets. They have not released the caliber used in previous shootings, either.
Investigators will be searching the I-95 area for evidence, which could cause major traffic backups in that area.
The museum will be closed Friday while police and the FBI investigate. No one was hurt in the most recent shooting incident, and none of the artifacts inside the museum suffered damage, according to officials.
Ballistics testing has determined that the shots fired in all three previous incidents came from the same weapon and that the shots were fired into vacant parts of the buildings. No one was injured in any of the incidents.
Property damage at the Marine recruiting office at 13881 Metro Tech Drive was reported at about 8:30 a.m. Tuesday when an employee discovered two bullet holes in a window.
Authorities had already determined that the shots fired at the National Museum of the Marine Corps on Oct. 17 and the Pentagon on Oct. 19 came from the same weapon.
Several glass panels at the Marine Corps Museum were discovered to have been struck the morning of Oct. 17, but none of the museum's artifacts was affected.
Then just before 5 a.m. on Oct. 19, officers at the Pentagon reported hearing shots in the area of the south parking lot. Fragments of two bullets were found embedded in windows on the third and fourth floors. They shattered but didn't penetrate the reinforced-glass windows, which were part of unoccupied offices. Four other bullets struck the Pentagon's façade.
In the wake of the shootings, security is being stepped up for Sunday’s Marine Corps Marathon. The Pentagon was the most prominent target, and more than 30,000 marathon runners will be speeding right by the Defense Department headquarters on Sunday.
The Pentagon Force Protection Agency said it will provide tighter security, particularly near the pre-race staging area on the Pentagon’s north parking lot, though officials insist there is no known threat for the marathon.