WOODBRIDGE, Virginia (CNN) -- Ballistics test results link four shootings at U.S. military facilities in the Washington suburbs in October, and investigators are probing whether a new case at a Coast Guard recruiting office is related, police in Virginia said Tuesday.

The latest incident was reported Tuesday morning after a bullet struck the recruiting office, housed in a Woodbridge strip mall. The description is "relatively similar" to October cases in which shots were fired at the Pentagon, the National Museum of the Marine Corps and a vacant Marine recruiting station, said 1st Sgt. Kim Chinn, spokeswoman for Prince William County police.

"Employees of the Coast Guard recruiting station called to tell us there was some damage to the glass, and police arrived and determined it was probably done by a bullet," Chinn said.

She said the shooting left a mark on the glass. "It did not penetrate the glass, more like a graze," she said.

No one has been injured in any of the incidents, which began when six shots were fired at the Pentagon early on October 19, authorities have said. Ballistics tests have connected that incident to shots aimed at the Marine museum on October 17 and 29, as well as to an October 25 case in which shots were fired at a Marine Corps recruiting station in Chantilly, near Washington Dulles International Airport.

Chinn would not say how many bullets were found at the scene Tuesday. The Coast Guard referred questions to the FBI, saying it is taking the lead in the investigation. The FBI said it has sent personnel to the recruiting center.

The Pentagon Force Protection Agency has declined comment on the shooting.

-- CNN's Brian Todd, Adam Levine, Padma Rama, Mike Ahlers and Carol Cratty contributed to this report.

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