It happened at 7:35 a.m. Wednesday on South Main Street in Camden, Delaware.
Police say the bus carrying about 40 students was enroute to the Fred Fifer III Middle School when the driver began to experience some kind of cardiac distress.
The bus, which was traveling north, veered across the southbound lane, sideswiped a utility pole, and traveled about 90 more feet, hitting a house and a tree.
Police say a Dover fireman who witnessed the crash rushed over to the scene, pulled the driver from the bus, saw he was experiencing cardiac distress and starting performing CPR.
Medics arrived and rushed the man to Kent General Hospital in Dover, where he later died. The Delaware Medical Examiner has yet to determine the exact cause of death. His name has not been released.
Three students were taken to the hospital to be treated for minor injuries.
Delaware State Police and Camden, Delaware Police are investigating. No charges are expected to be filed.