The death of a Legacy High School bus driver and mother has been ruled an accident.

According to an autopsy and toxicology report obtained by 9NEWS, Kari Chopper, 43, had no drugs or alcohol in her system at the time of her death.

On Sept. 11, a bus full of Legacy High School football players and coaches went off the roadway near DIA.

Chopper was pronounced dead at the scene.

Fifteen students and three coaches were injured in the crash.