Police investigators have ruled the death of an Akron bus driver an accident due to human error.A month after Laura Zborowski, 51, died outside Middlebury Academy in Akron, a police report indicates that an evacuation drill went awry when a bus brake was released due to “human error” while a 10-year-old student was still aboard.The student ran toward and jumped from the rear door, where witnesses and police have said Zborowski threw the child to safety before being pulled under the bus and killed.She was pronounced dead on arrival at Summa Akron City Hospital.