A Mississippi mother and her 3-year-old son were killed late Friday night when their vehicle struck a tree.

Mississippi Highway Patrol troopers report they don’t know what occurred to cause Leanna Washington’s vehicle to leave Mississippi Highway 27 in Hinds County at approximately 11:15 p.m.

The vehicle then struck a tree. Washington lived in Utica and was 27 years-old.

Troopers report that neither Washington nor her son LeCheston Roberts was wearing any kind of seat belt or child restraint.

A third occupant in the vehicle, a child who was in a child safety seat, survived and was transported to the University of Mississippi Medical Center in Jackson.