Police are searching for three men they believe are responsible for the shooting along the 3000 block of Chestnut Street.
Investigators say a shootout happened Saturday around 12:30 a.m. between one man outside the post office and several others in a car.
At least four bullets hit the building with employees inside at the time, but no one was hurt.
Officials are looking through surveillance videos for more information.
So far, no arrests have been made at this time.