The fatal accident occurred Thursday morning along the 300 block of Kennedy Drive.
Officials say a postal worker was in his truck delivering mail. After placing mail into a mailbox, the driver, a 53-year-old man, began to pull away to proceed to the next house.
This is when, authorities say, the vehicle struck the 2-year-old boy who had crossed in front of the mail truck unseen.
The child was transported to Paoli Trauma Center where he succumbed to his injuries.
The investigation continues, but at this time no charges are pending against the driver.
The Downingtown Police Department were assisted by the Chester County Serious Crash Assistance Team.