Some of the roads in the area were closed for roughly four hours.
Authorities later identified the driver as Anthony Oglesby Jr., 34, of Bowie, Md.
State police said in a statement that Oglesby was a sergeant for the U.S. Navy Police and was on duty at the time. He was driving a marked patrol car.
The incident remains under investigation. Police said his body was sent to the Office of the Chief Medical Examiner for an autopsy.