Police said the truck was heading southbound toward Washington Square and left the scene after the crash.
Frinke's injuries are non-life-threatening in nature, police said.
On Tuesday, police released a picture of the vehicle involved in the crash. Anyone with any in formation about the hit-and-run is asked to call the Norwich Police Department at 860-886-5561 or U.S. Postal Inspector Brendan Murphy at 860-524-6084.
Frinke has been with the Postal Service since last September.
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