Florida ? A truck driver who plowed into a car at a school bus stop last week, killing seven children, had been awake for 34 hours, except for a short nap, an investigator with the National Transportation Safety Board said Friday.

Alvin Wilkerson, 31, was driving a load of bottled water from High Springs to Jacksonville, a distance of 85 miles, when he crashed into the other vehicle.

David Rayburn, the NTSB’s lead investigator in the crash, said fatigue was one of many factors being reviewed.