DALLAS -- The man charged with the murder of a U.S. Postal Service employee fired the deadly shots over a road rage incident, according to a statement released Thursday afternoon from the Department of Justice.

Donnie Ferrell, 25, told witnesses he shot at a postal service truck early Monday morning because he claimed the driver, Tony Mosby, made a hand gesture toward him, the statement alleges. Mosby was struck in the head by one of the several shots that were fired at his vehicle.

A $50,000 reward was offered for information into the death of Mosby, who was shot and killed at about 2:30 am. Monday while driving a postal service truck near the I-30 and I-35 interchange of Dallas.

postal truck_1519035201537.JPG.jpg

Authorities say two witnesses came forward Wednesday. According to the Department of Justice, the witnesses told FBI investigators that they were with Ferrell the night before and into the early morning when the shooting occurred.

The witnesses said they were inside a vehicle with Ferrell when the driver attempted to go around the USPS truck while driving erratically.

"Moments later, Ferrell fired several shots from a handgun in the direction of the USPS truck," read the statement form the Department of Justice. "The occupants of the vehicle observed smoke and sparks coming from the truck and the truck eventually crashing into the barrier. One of the occupants asked Ferrell why he had shot the gun toward the truck and Ferrell responded that the driver of the USPS truck had made a hand gesture towards their vehicle and that angered him."

Ferrell, of Hutchins, was arrested and charged with one count of murder of an officer or employee of the United States.