The crash was reported shortly before noon on Tuesday, April 15, after the train left the Manassas station, striking the truck at a nearby crossing.
Investigators say the truck was thrown off the tracks coming to rest in the right of way.
First responders rushed to the scene and had to extricate a person trapped inside the truck who was then taken to an area trauma center with what were described as "serious injuries."
The tracks were shut down to allow responding crews to access the truck.
Officials said the Amtrak train remained at the scene while police investigated. It was not immediately clear why the driver attempted to cross.
The incident remains under investigation.
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