Maryland State Police responded Saturday evening to a shooting on the shoulder of the ramp from northbound Route 3 to Interstate 97 near Millersville.
Troopers say they were told that a road rage incident had happened between the two vehicles before they pulled over and the shooting occurred.
Troopers believe the driver of a minivan, 40-year-old Joseph Walker of New Jersey, shot the driver of a Honda, 36-year-old Joseph Harvey Jr. of Millersville, after Harvey approached the minivan. Harvey later died.
Troopers charged Walker on Sunday with second degree murder and manslaughter. He is a sworn officer with the Hudson County Prosecutor's Office in New Jersey.