The FBI is investigating the shooting of an Air Force helicopter over Middleburg, Virginia, on Monday — an incident that injured a member of the crew.

A UH-1N Huey helicopter assigned to the 1st Helicopter Squadron at Joint Base Andrews was on a routine training mission when it was hit by a bullet from the ground, the Air Force tells DCist/WAMU in a statement. The helicopter was about 1,000 feet in the air when it was shot and sustained some damage. It’s unclear who fired the bullet.

A crew member was hurt in the incident, and the helicopter conducted an emergency landing at Manassas Regional Airport at 12:43 p.m. Monday. Roughly 20 minutes earlier, airport officials had received a call from the airport’s control tower about an inbound military helicopter with an emergency on board, per ABC News.

The injured crew member, who was not identified, was then treated at a hospital and released. The person was said to have a bleeding hand, Air Force Times reports.

Agents from the FBI’s Washington Field Office traveled to the airport after receiving reports about the shooting, the bureau told the Associated Press. The FBI is encouraging those with information about the incident to call 202-278-2000.