Police say the driver of a van that overturned on Interstate 95 in Virginia, killing six people, has been charged with six counts of involuntary manslaughter.

Virginia State Police said in a news release on Sunday that driver fatigue is being considered as a factor in the crash, which occurred early Saturday morning in the Bowling Green area, about 20 miles south of Fredericksburg.

Police say Wenceslao Cruz-Marquez of Chicago was driving the van, which had 15 passengers. No one was wearing a seat belt. Police say the group was on the way to New Jersey from North Carolina.

The six people killed included four men, one woman and one child. All were thrown from the van and died at the scene. The survivors were taken to hospitals.