The driver of the truck was killed after the vehicle was struck by the lead locomotive of the Union Pacific train, a railroad spokesman said.
Authorities received a call at 5:59 a.m. about the collision at an uncontrolled crossing on Hogarth Street in a portion of the city of Eau Claire in Chippewa County.
Once the train stopped, it blocked crossings at Hogarth, Melby Street and Delbert Road. Eau Claire police said the crossing at Melby Street west of Business 53 re-opened at about 10 a.m. Hogarth Street re-opened after 1 p.m.
The truck, carrying U.S. mail and packages, was operated by a highway contract route driver employed by Mack Priority Transport, according to the U.S. Postal Service. The Postal Service expected delays to the mail from routes in Osseo, Whitehall, Independence and Pigeon Falls served by the truck.