The crash happened after 10 a.m. on Main Street.
The mail carrier apparently suffered some sort of medical emergency behind the wheel, causing him to lose control of the vehicle.
Richardson says that first responders were on the scene within minutes.
“They got to him as quick as they could, got him out of the vehicle,” said Richardson.
The driver was taken to the hospital for treatment. But officials now say he has died.
The Westmoreland County Coroner’s Office has identified the postal worker as 47-year-old Ronald Sopko, of Murrysville.