Washington (CNN) -- The FBI is investigating shots fired Monday night or early morning Tuesday at the Marine Corps recruiting station in Chantilly, Virginia, the bureau announced.
The overnight shooting is the third such incident at a military-related building in the past two weeks, according to an FBI news release.
Last week, a gunman fired several shots 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.
Ballistics tests are under way for the most recent shooting, the bureau said. Two shots hit windows of the recruiting station, and another bullet struck the window of a nail salon in the seven-unit business building, authorities said.
The shots were believed to have been fired between 8:30 p.m. Monday and 8:30 a.m. Tuesday, said Mary Ann Jennings, a spokeswoman for the Fairfax County Police Department.
"It's pretty scary. I"m really grateful that it happened at night," said Mari Bever, manager of a pet care business next door to the Marine facility. If the person who fired the shots is trying to make a statement about the military, she said, "I don't think they are going about it the right way."
Officials do not know whether the three incidents are connected, Jennings said.
Officers believe they had found all bullet locations at the recruiting station, a law enforcement official said. Portions of the rounds were recovered for evidence, the official said, and will go to the FBI lab in Quantico, Virginia.
The official did not have any information on whether investigators have recovered security camera footage from any businesses.
Six shots were fired at the Pentagon shortly before 5 a.m. October 19. Two of the bullets struck exterior windows at a section of the building that is being renovated, and the other four hit the building's facade, Steven Calvery, director of the Pentagon Force Protection Agency, said in a statement at the time.
The Marine museum shooting took place between 12:15 a.m. and 5 a.m. October 17, when the building was unoccupied, director Lin Ezell said. Ten bullets were fired, authorities said, five hitting windows and five hitting metal panels.
Investigators said at the time of the earlier shootings they believed both came from assailants with rifles, but the FBI did not release any information Tuesday about weapons or caliber of ammunition "to preserve the integrity of investigative efforts."
Calvery referred questions about whether the Pentagon was increasing security in the wake of the shootings back to the statement he made October 19.
"I personally think that our security is pretty robust at normal times," he said at that time. "We are still evaluating whether or not we need to do anything additional to ensure security of the Pentagon. Right now, we think our protective measures are adequate."
CNN's Larry Shaughnessy and Carol Cratty contributed to this report.