DALLAS — The Latest on the arrest of a man in the shooting death of a postal worker driving on a Dallas highway (all times local):

3 p.m.

Authorities say a man arrested in the fatal shooting of a postal worker driving a delivery rig on a Dallas highway may have been acting out of road rage.

The U.S. attorney’s office released details of the investigation Thursday into the arrest of Donnie Ferrell for the shooting death of Tony Mosby early Monday morning on Interstate 30. Investigators say two witnesses came to the FBI’s Fort Worth field office Wednesday saying that they were in the car with Ferrell when he fired the shots at the truck.

They say Ferrell claimed Mosby made a hand gesture at them as they tried to pass his truck and he fired the gun out of anger.

Ferrell is scheduled to appear in Magistrate’s court Thursday to face a charge of murder of a U.S. government employee who was performing his duties.

11:40 a.m.

Investigators have arrested a man who they say shot and killed a postal worker while he was driving an 11-ton (10-metric ton) delivery rig on a Dallas highway.

U.S. Postal Inspector Amanda McMurrey says postal inspectors in cooperation with the Dallas Police Department arrested 25-year-old Donnie Ferrell of Hutchins. McMurrey says federal authorities will determine the exact charges, but Ferrell will appear before a U.S. Magistrate judge Thursday.

Federal investigators had offered a $50,000 reward in the early Monday shooting that left 58-year-old Tony Mosby dead.

Investigators say Mosby was driving the rig, known as a box truck, when he was shot. He was found dead in the truck, which had crashed into a guardrail on Interstate 30 near downtown Dallas.