It happened in the 2000 block of Porter Street SW in front of Our Lady of La-Vang Parish.
The accident happened at 6:34 p.m. For a period of time the road was blocked off from the Church to Avon street but one lane later reopened to traffic.
According to the Wyoming Police Department, Louis Van Vo, 77, was attempting to cross Porter to attend a church service when he was hit by the US Postal Service truck, which was westbound in the curbside lane on Porter when the acccident occurred.
Witnesses told police that they observed Vo crossing northbound from a parking lot on the south of Porter Street SW, but he was unable to make it across the roadway before being hit.
Vo was pronounced dead at the scene.
The mail truck driver was not injured.
The accident remains under investigation by the Wyoming Police Department.